[glc]

The motherboard and power supply I recommended are not SLI-capable. You need to increase your budget or forego SLI. If you want to max out the memory, you DEFINITELY need 64 bit, and I'd recommend 8 gigs now. Also, you should get a different processor if you plan on overclocking.

Newegg.com - GIGABYTE GA-Z68X-UD3-B3 LGA 1155 Intel Z68 SATA 6Gb/s USB 3.0 ATX Intel Motherboard

Newegg.com - Intel Core i5-2500K Sandy Bridge 3.3GHz (3.7GHz Turbo Boost) 4 x 256KB L2 Cache 6MB L3 Cache LGA 1155 95W Quad-Core Desktop Processor BX80623I52500K

Newegg.com - CORSAIR Vengeance 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model CMZ8GX3M2A1600C9R

Newegg.com - Antec High Current Gamer Series HCG-750 750W ATX12V v2.3 / EPS12V v2.91 SLI Certified CrossFire Certified 80 PLUS BRONZE Certified Active PFC Power Supply