If you have sufficient cash flow I would suggest following configuration.
Intel Core 2 Quad Q9650 Processor
Asus Striker II Formula Motherboard
Corsair TWINX Dominator Dual Channel 4096MB PC12800 DDR3 1600MHz Memory (2 x 2048MB)
2 x Palit GeForce GTX 280 Video Card - 1GB DDR3, PCI Express 2.0...