Basically what kenork said except I would want 2 5870HD in Crossfire instead of a single 5970HD. I am currently contemplating whether or not I should get am i7 980X when it comes out.
Well as this thread is basically going to list the very best commercially available and well known equipment you would want 2 5870's in Crossfire. The Crossfire system allows you to use 2 graphics cards at the same time and is an AMD product so the only GPUs it can use are ATI.
Intel i7 980X
EVGA 4-way SLI classified
Lian-li Tyr X2000 case
Thermaltake 1200 watt PSU for....
4 GTX 495's! (The inevitable)
And 12 gigs of 2000 ddr3 (I'd put 24, but I'm not doing any processing just gaming)
Oh and 512 gigs of SSD memory for my games
And 8 tb HD for my porn movie collection
16 KB of rom, 16 KB ram, 3.5 mhz CPU, OS: Sinclair BASIC, 32 columns × 24 rows of characters on screen at any time, seven colours at two levels of brightness each, plus black and an image resolution of 256×192.
i7 980X processor 4GHz
24 bg RAM
4 ATI Radeon 5970 in crossfire
Liquid cooling
1200W PSU
2 Terabytes of hard drive space
And an epical case with an epical borderless screen