http://www.wowwiki.com/Four_Horsemen_%28original%29
http://www.tentonhammer.com/node/26652
4 bosses: Ragnaros, Meteor, Green Beam and Void Zone:
Raggy puts fire dot on tank, meteor summons meteor (Stack on tank), green beam you gotta avoid chaining :D and void zone you move out of.
Ok enough with the obvious shit; everyone needs Fire Protection pots here, Shadow too but in all Liklehood most of the dmg you will take is gonna be fire.
Dps Rotation:
You guys have the easiest job by far. Normally DPS can use a 3 boss rotation but suffice to say, for learning this encounter we will use 2 boss. Obviously we will hit enrage but better to have 40 alive at that point :D Normally we could split into 4-5 dps groups but I think for 2boss rotation, we can try a split of 7/73, ie 3 groups.
This means you have one on Meteor, on group on Ragnaros and one idle. There are three important things for you to remember here:
1) BEFORE YOU RUN IN TO DPS METEOR BOSS MAKE SURE YOU ROLL WITH THE INCOMING METEOR TANK (if he gets hit for 12k gg!)
2) BEFORE YOU RUN OUT FROM METEOR BOSS MAKE SURE YOU STACK ON TANK TILL HE CASTS IT, THEN MOVE OUT (its 12-15sec timer so if one is cast then u get mark, obviously u can move out but be aware if its coming and ur moving - your best bet is to see if the other group are moving in, then u can move out with your tank)
3) Never EVER go above 3 marks, always try to move out on 2 or you screw the rotation for the others. You wil have some healers but not much. Also in the safe spot, you can use things like bandages/lightwell (EVEN FD DRINK ROFL!)

Were trying 3 dps groups; Group a - 7 dps, group b - 7 dps, group c - 6 dps
At start:
Idle - group (c)
Meteor - group (a)
Ragnaros group (b)
0:32 secs, 2 marks:
Idle - group (b)
Meteor - group (c)
Ragnaros - group (a)
0:54, 4th overall mark
Idle - group (a)
Meteor - group (b)
Ragnaros group (c)
etc, rotate like that. A few tries and you will get this, easy job for you. But as mentioned before, on peenix we will prolly wipe like this from enrage/lack of damage. Atm its about surviving and getting tank rotations 100%