500 Budget Gaming pc

you don't need the DVD drive or OS, but what about a monitor?

assuming you don't need a monitor, thsi is after rebates:

PCPartPicker part list / Price breakdown by merchant / Benchmarks

CPU: Intel Core i3-2120 3.3GHz Dual-Core Processor ($116.99 @ SuperBiiz)
Motherboard: ASRock H61M/U3S3 Micro ATX LGA1155 Motherboard ($59.99 @ Newegg)
Memory: PNY Optima 8GB (2 x 4GB) DDR3-1333 Memory ($37.98 @ Outlet PC)
Storage: Seagate Barracuda 500GB 3.5" 7200RPM Internal Hard Drive ($59.98 @ NCIX US)
Video Card: XFX Radeon HD 6870 1GB Video Card ($144.99 @ Newegg)
Case: Rosewill R101-P-BK MicroATX Mid Tower Case ($33.98 @ Newegg)
Power Supply: XFX 450W ATX12V / EPS12V Power Supply ($44.99 @ NCIX US)
Total: $498.90
(Prices include shipping and discounts when available.)
(Generated by PCPartPicker 2012-08-14 17:18 EDT-0400)