PCPartPicker part list:
http://pcpartpicker.com/p/DtTa
Price breakdown by merchant: http://pcpartpicker.com/p/DtTa/by_merchant/
Benchmarks: http://pcpartpicker.com/p/DtTa/benchmarks/
CPU: Intel Core i3-3220 3.3GHz Dual-Core Processor ($123.79 @ Amazon)
Motherboard: ASRock H77 Pro4-M Micro ATX LGA1155 Motherboard ($89.99 @ Amazon)
Memory: Crucial Ballistix Smart Tracer 4GB (2 x 2GB) DDR3-1600 Memory ($25.98 @ Outlet PC)
Storage: Western Digital Caviar Blue 500GB 3.5" 7200RPM Internal Hard Drive ($59.57 @ Amazon)
Case: Apex PC-389-C ATX Mid Tower Case ($31.24 @ Amazon)
Power Supply: Corsair Builder 430W 80 PLUS Bronze Certified ATX12V Power Supply ($29.99 @ Newegg)
Optical Drive: Samsung SH-224BB DVD/CD Writer ($15.98 @ Outlet PC)
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit) ($89.98 @ Outlet PC)
Total: $466.52
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2013-02-14 08:37 EST-0500)
Here is a Intel build, you could go AMD for a cheaper build.