I am currently building a new comp with these specs: Core i5 750 (2.66) gonna be overclocked to 3.2
ASUS P7P55-D-E DELUXE
GTX 480 2 WAY SLI
2 WESTERN DIGITAL CAVIAR BLACK 1TB DRIVES
3X2GB G.SKILL DDR3 RAM
Tripple Channel Ram is meant for the 1366 Socket, you are looking at the 1156. If you're certain on the 1156, I would go to 2*2GB ram, otherwise you will be looking at 2*2 plus 1*2, which will likely run slower than just going with the 4GB.
A better (IMO) idea would be to go to the 1366 Socket, with a 950. Google "1156 PCI lanes" to get an idea of what I mean, especially with a USB3.0 board and 2 480's.
Regarding power, are you looking at overclocked 480's, either yourself or factory?