Pr0, I'm in the middle of monster build myself....i'm looking for more of workstation machine then gaming. But if was to build a gaming machine, i would go this route:
Mother board:
Asus Rampages II Extreme (Top gaming board at the moment)
http://www.newegg.com/Product/Produc...82E16813131352
CPU
Core i7 920...the motherboard above that i mentioned is an overclocking beast...so i would go with a core i7 920.
http://www.newegg.com/Product/Produc...82E16819115202
Video Card
Buy two of these...EVGA GTX 295 (since you're saving on the CPU)
http://www.newegg.com/Product/Produc...82E16814130449
Ram
Corsair Dominator Triple Channel 1800 6gig
http://www.newegg.com/Product/Produc...82E16820145232
Case, harddrive, and the rest...not going to worry about those at the moment.
Remember two things. That gaming motherboard above is slightly bigger then the typical. So your case will have to suit EXT boards. Also, make sure your friend knows about voltages (and what hardware takes which voltages) when in the bios.