Depends alot on your budget, the problem is we would need to eliminate the CPU bottleneck. How about trying those new i7 with compatiable motherboard from Gigabyte?
Core i7 CPU with, Asus P6T Deluxe, Gigabyte UD5, or EVGA x58 will do the trick. If you want to have the baddest thing on the block, the Asus P6T6 WS Revolution or possibly the EVGA Classified which should be out soon.