I remember reading this a few years ago on Metal Storm.

I give you …
The 101 Rules of Progressive Metal 

1. Insist that your definition of prog metal is sacred and that the only progressive bands are the one you deem to be so.
2. Accuse anyone who disagrees with you regarding rule 1 of lacking musical intelligence and not being a true prog fan.
3. Have contempt for mainstream music.
4. Insist that most people listen not to the music, not to the lyrics but only the chorus and that is why prog metal is not mainstream.
5. Accuse anyone who disagrees with you regarding rule 4 of lacking musical intelligence and not being a true prog fan.
6. When showcasing a new prog metal band to a non-musician friend, put on the most technically difficult song, and skip directly to the solo part.
7. If your friend says that it is cool, tell him that he has grasped the grandeur of prog and shown that his intelligence is superior to that of the mainstream sheep.
8. If he doesn´t, accuse him of lacking musical intelligence and not being a true prog fan.
9. Renounce all contact with friend in rule 8. Racial purity isn´t all bad.
10. Make sure your drummer has a double bass pedal.
11. If he hasn´t, kick him out and get another one who has. Single pedal is NOT prog.
12. Own every side-project a member of Dream Theater has been involved in. Listen to approximately none of them regularly.
13. When a mainstream fool asks you what prog metal is, tell him something along the lines of “prog is the evolution of musical expression and experimentalism in rock.” In any case, make sure that the person in question is left with no idea of what prog metal is. He wouldn´t have understood anyway.
14. Insist that music should always progress, although as long as you write an album in the prog vein, you don’t necessarily have to.
15. Accuse anyone who disagrees with you regarding rule 14 of lacking musical intelligence and not being a true prog fan.
16. Refer to progressive metal as intelligent music for intelligent people, preferably at every occasion where a mainstream group or genre is mentioned.
17. Note that the above does not qualify as arrogance any more than pointing out that wine is drink for the more sophisticated.
18. A song under four minutes is NOT prog. If you are stuck with a song under four minutes, insert a phrygian solo trade-off between the guitarist and keyboardist as long as needed.
19. If a mainstream fool tells you that shredders are mindless w**kers, tell him that “at least they can tune their guitars, har har”, and walk away defiantly.
20. Spocks Beard is NOT prog. If anyone disagrees, kill them.
21. Humming along with the melody to a prog metal song is forbidden. Burn all albums you own with hum-along melodies.
22. Loathe all music you used to like before you got into prog. This is not optional. When asked why, tell people that “I am into GOOD music now, why would I go back?”.
23. Accuse any prog metal musician that cuts his hair of selling out.
24. Often state that you don´t only listen to prog. Jazz is a good choice.
25. Yeah…like you have more than 3 jazz CDs in your collection…
26. Never accept ANY Berklee graduates. The drop-outs are so much better.
27. Riffs in 4/4 are not progressive. If you happen to come up with a cool riff in 4/4, alternate between 4/4 and progressive time signatures like 7/8 every other measure to ensure the musical complexity synonymous with prog metal.
28. Be able to mention 20 bands noone has heard of, not even true prog fans. Own no releases of these bands.
29. Get an Ibanez. This is not negotiable.
30. Spend 5 hours every day critiquing other musicians on forums.
31. Spend 5 minutes every other day actually practicing your instrument.
32. Yell at people who headbang at concerts: They`re not prog enough to get the music, what do they expect?
33. Sus4 is your friend. To ensure that your album is a true progressive release, include at least one part where the keyboard plays ascending sus4 chords over a single-note broken rhythm in 7/8.
34. Make sure your bandname is either a
a) Oxymoron
-Silent Noise
-Tender Harshness
-Healing Gun
b) Some geeky sounding name ripped from some obscure book.
-Deitronus
-Tarakoch
-Fentaran
c) Random combination of at least 2 three-syllable words.
-Eternal Twilight Tranquility (Can`t get much progger than that)
-Redolent Arithmetic
-Evolution of Vernacular Domesticated
35. Don`t worry about if your band name makes any sense or not. Since 90% of your fanbase is from Brazil and Japan, you can safely ignore conventional English grammar and instead focus on what´s really important: The lyrics (see rule 36).
36. Write deep and ambiguous lyrics.
37. If unable to write deep and ambigous lyrics, include at least one of the following phrases to ensure recognition as lyrical genius in prog circles:
“I`m staring towards ascension divine, caught in my own revelation, a nightly mystery of soulburning apparition”
“Mornings` gentle caress, a ray of sunlight enveloping the spirit of the sleeper ventriloquist”
“A timid, palatable genocide, turn towards the decline of mankind, the festering wound of ages past changes into the soul-spirit of vestigial sentences.”
38. Use a non-standard instrument like violin, saxophone or kazoo, regardless of how idiosyncratic it turns out to be. This constitutes being prog.
39. Make sure your bass-player has as many strings as possible. Don`t worry if he uses approximately three of the 11 strings on his custom Carvin 30 kg bass regularly, just give him a bass solo in the middle of your mandatory instrumental tune(more on that later)where he can really show the extent of his instruments capabilities. Imagine the range of scales on an instrument like that!
40. Release a live-album called “Live in Tokyo”.
41. Change time signatures. Constantly.
42. Accuse anyone who does not do so of lacking musical intelligence and not being a true progressive musician.
43. Your amp MUST be a Mesa Boogie. If a friend of yours tries to convince you´re wrong and you should check out his Marshall tell him that his tone is thin and buzzy.
44. State that Metallica can´t properly tweak the boogies. They´re so… unprog!
45. Start a Dream Theater cover band with friends just starting out playing instruments. Spend half of the rehearsal talking sh*t about punk bands and how people don`t understand your music.
46. Play a sh*tty version of a humongously difficult DT song at a Battle of the Bands-type contest. Metropolis Part 1 or Dance of Eternity are both good choices, as is Erotomania.
47. When your band ends up last, shift all blame over to the judges; hey, they have no idea what good music is! Why else would they let that boring pop band win?
48. Talking about starting playing an instrument; always start with the most technically difficult song you know. Remember, this is a testament to your immense talent, so be sure to mention this on every internet community you happen to frequent.
49. When are you able to play something at half speed very sloppy, proudly state that you “nail” the song in question.
50. People are bound to ask for a recording of the feat mentioned in rule 49. However, you are not able to provide it to them, because a) your recording equipment got dissolved by digestive acid yesterday, you don`t need to prove anything to people. Your word should be good enough c) you don`t know anything about computers (even though you sit by one most of the day), as you spend most of your day practicing your instrument.
51. Tool is NOT prog. If anyone insists they are, kill them.
52. Hate Falling into Infinity. If the feeling that you actually enjoy FII(even the “proggier” songs like TOT)sneaks up on you during a glitch of concentration, remind yourself that DT sold out.
53. Actually, state that DT sold out on every good occasion. This means every time their name is mentioned.
54. Don´t be John Arch. Insist that any pre-Alder Fates is 100% not prog.
55. Do not move on stage. Don`t under any circumstances forget that nobody at prog concerts pays attention to the audience, including the band.
56. The best songs are those that are over 15 minutes, have multiple named sections, and have solos by everyone in the band INCLUDING the drummer.
57. Accuse anyone who disagrees with you regarding rule 56 of lacking musical inteli…Yeah, you`ve got it now, haven`t you?
58. Never ever under any circumstances say “Six Degrees Of Inner Turbulence ruled.”
59. Never let anyone tell you that Dave Weckl is better than any prog metal drummer. If they still insist, don`t kill them, but rather put on the Mike Portnoy drum solo from 1993`s “Live in Tokyo” vid, which still today is the benchmark for good drumming, REGARDLESS of genre.
60. It would still be a good idea to have that gun ready, though.
61. Drummers: Huge kits are MANDATORY!!!! If all you have is a 4-piece with 3 crappy cymbals, then you don´t belong on stage. A 5-piece single bass drum kit is the bare minimum and even that´s on the edges of bare bones. If you have a tiny kit BUY MORE DRUMS AND CYMBALS!!!!!!!
62. No, 6 toms are not enough, MORE DRUMS AND CYMBALS!!!!
63. Reform with old members and release an album intended to make up for years of bad reception from fans (see Yes) or claim your next album will be a return to past glory (see Queensryche). If it flops, be sure to blame a producer or record company.
64. When someone asks you why prog metal isn`t more popular if it is so darned good, tell them that it is because “it is over the mainstream peoples heads”.
65. Talent = Technical skill. Hail any band with lightning-speed solos for their immense talent.
66. Publicly state that your band is non-religious, then make many religious and/or spiritual allusions in the lyrics.
67. Stress your openmindedness. State that you like all forms of music, except lower forms of music like pop, rock `n roll, blues, techno, trance, rap.
68. Accuse fans of the aforementioned genres of not being openminded.
69. Get a Kurzweil. As the undisputed <<>>, Jordan Rudess plays it, you have no choice but to get one yourself, no matter what synthezisers you actually like. ALL BOW TO THE MIGHTY 88-KEY <<>> KURZWEIL!!!
70. ALL GLORY TO THE HYPNO-KURZWEIL!!!!(Futuruma fans will know what I`m talking about)
71. Show off with your equipment. Show off with your playing/singing. Show off with your *ahem* length. Show off with your girlfriend. Show off with anything you can think of. Show off with your DOG for god´s sake.
72. Get a dog.
73. Play air-drums or air-guitar at concerts. This will make sure that other prog fans recognize your immense talent.
74. Stuck in song-writing? Insert a part with a slow single-note gallop rhythm where the singer yells “ENTER THE SUUUNNNNNNNN” several times.
75. Note that you can substitute “ENTER THE SUUUNNNNNNNNN” for either of the following: “FATHER, MY ADOLESCENCY IS AGONNNNNYYYYYYY” or “THE APPARITION DIVIIIIIINNNNEEEE”. All three are suitable choices.
76. What do you mean, you haven`t trigged your bassdrum?
77. Remember, faster=more progressive. Slow songs cannot be progressive, best example would be Pink Floyd.
78. If anyone says PF are prog, kindly refer them to rule 1 while you prepare to do a “Varg”, so to say.
79. During recording, make sure that you accuse the producer, the recording engineer and half of your band of not playing the song properly at least once.
80. Make sure your album cover contains either a psychedelic computer-drawn image, a lavish painting with mythological figures, or is illustrated by Travis Smith.
81. Write epics.
82. In case you didn`t know, epics must be about adolescency, concerning a legend, or a deep dystopian tale where a cheesy fictional city/world/pizza shop serves as a metaphor for this world.
83. Have racks with loads of equipment.
84. Have racks without equipment. Who is going to see them if you don`t display them?
85. No intro for your song? Insert a single-note broken rhythm accented on the snare, with shifting keyboard chords underneath.
86. Refuse to lend prog CDs to mainstream friends. When asked why, tell him/her that (s)he “will understand when (s)he matures”
87. When playing ANY gig, from the lowliest bar to the most gargantuan arena, be sure that no member of the audience will leave without having heard every lick you are able to play.
88. Have at least 5 solo spots during a concert.
89. In case you have forgotten while reading this, prog metal is intelligent music for intelligent people.
90. No, Marillion is not prog. I kindly refer you to rule 20.
91. BOOOM!!!
92. Buy new albums from past prog-greats.
93. When they turn out to be crap and nothing like the old albums, hit yourself in the head with a hammer until you like them.
94. Hold that there is no bad prog, only DIFFERENT.
95. Of course, that only applies to bands you like. See Rule 1.
96. In case you wondered, Dream Theater is and will always be the benchmark for prog metal. The more something sounds like Images and Words, the more progressive it is.
97. Proclaim Rule 96 to people with a straight face in all seriousness. This is not optional.
98. Have side-projects. Make sure that all side-projects consist of pointless jamming over endless repetitions of clicheed riffs.
99. Make sure that at least one of your side-projects feature Mike Portnoy on drums.
100. If you cannot get Mike Portnoy, get someone who sounds like him.
101. You mean you have been reading this when you could have been practicing along to Metropolis Part II or composing a sidelong epic? For shame!!!!

Source: http://www.metalstorm.net/pub/fun_comments.php?fun_id=3