PCPartPicker part list:
http://pcpartpicker.com/p/Dw1G
Price breakdown by merchant: http://pcpartpicker.com/p/Dw1G/by_merchant/
Benchmarks: http://pcpartpicker.com/p/Dw1G/benchmarks/
CPU: AMD Phenom II X4 965 Black 3.4GHz Quad-Core Processor ($98.24 @ Amazon)
Motherboard: Gigabyte GA-78LMT-S2 Micro ATX AM3+ Motherboard ($49.99 @ Amazon)
Memory: G.Skill Value 8GB (1 x 8GB) DDR3-1600 Memory
Storage: Toshiba 500GB 3.5" 7200RPM Internal Hard Drive
Video Card: Asus Radeon HD 7850 1GB Video Card ($190.95 @ Amazon)
Power Supply: XFX ProSeries 450W 80 PLUS Bronze Certified ATX12V / EPS12V Power Supply ($59.99 @ Amazon)
Total: $399.17
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-02-14 13:29 EST-0500)