New PC Build

[Snowball]

Very rough build, could definitely be optimized more for cost/performance ratio, but this build will have monster performance:

CPU: i7-930
Mobo: EVGA E760 CLASSIFIED
RAM: Corsair Dominator 3x2GB DDR3 2000 (you could double this if you want for ~$350)
GPU: 2 x EVGA GTX 480
HDD: 2 x WD Caviar Black 1TB (for storage)
SSD: Intel X25-M 80GB SSD (for OS and programs)
Case: Corsair Obsidian 800D (for air or water cooling)
PSU: Corsair 1000w 80+

Total cost comes out to $2,969.90 U.S., so you've got a bit of headroom to try other things or just save some money.  You can add your own optical drives and soundcard and what not, but I'd recommend either an after market cpu cooler like the Corsair h50 as previously suggested, or a full blown water cooling kit.  If you don't wc, you're gonna need to buy some fans to fill up the case and keep it nice and aircooled, especially with the SLI'd fermis (inb4 housefiresomebodycall911).

EDIT: If you want a USB 3.0/6GB/s SATA Mobo, consider the Asus Rampage III