Okay, I've came up with this. If you want, you can buy a refurbished hard drive and save a few more bucks. This build is pretty great for the price, but being you need an OS really kills it. It's a few dollars over budget, but its completely worth it!
PCPartPicker part list:
http://pcpartpicker.com/p/2NSs5
Price breakdown by merchant: http://pcpartpicker.com/p/2NSs5/by_merchant/
Benchmarks: http://pcpartpicker.com/p/2NSs5/benchmarks/
CPU: AMD FX-6300 3.5GHz 6-Core Processor ($114.48 @ SuperBiiz)
Motherboard: Asus M5A78L-M/USB3 Micro ATX AM3+ Motherboard ($64.98 @ OutletPC)
Memory: A-Data XPG V1.0 8GB (2 x 4GB) DDR3-1600 Memory ($69.99 @ Newegg)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($59.99 @ Newegg)
Video Card: Gigabyte GeForce GTX 650 Ti Boost 2GB Video Card ($169.99 @ Newegg)
Case: Silverstone PS08B (Black) MicroATX Mid Tower Case ($34.99 @ Newegg)
Power Supply: Corsair Builder 500W 80+ Bronze Certified ATX Power Supply ($57.74 @ Amazon)
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit) ($91.48 @ OutletPC)
Total: $663.64
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-02-05 16:12 EST-0500)
If you can't find any 650ti Boost in stock, get a R7 260x.