Here are some choices...
CPU
Intel Core 2 Quad Q6600
Motherboard
Abit IP35/Pro
Gigabyte P35-DS3R
ASUS P5K/Deluxe
MSI P35 Platinum
EVGA 680i (if you want that SLI option)
RAM
2 x 1GB Crucial Ballistix DDR2-800
2 x 1GB Patriot Extreme Performance DDR2-800
GPU
8800GT
PSU
Corsair 520HX
Corsair 550VX
Rosewill RP550
XCLIO Greatpower 550
HDD
Seagate Barracuda 7200.10 320GB or 500GB
Western Digital WD7500AAKS 750GB
CPU Cooler
Tuniq 120
Thermalright Ultra-120 Extreme (no fan included)
Case (Personal preference)
Antec 900
Thermaltake Armor
Cooler Master 690
...or your choice
..oh...and Thermal Paste
Arctic Cooling MX-2
Arctic Silver 5
Any combination from that list of parts, is a great build. The rest of the peripherals would be up to you...like the mouse, keyboard, monitor, OS, etc...