Here's the super cheapo AMD build if you're looking to go around $600 with the OS ... you will give up a little bit on the CPU but it will still be a nice machine.
http://pcpartpicker.com/p/mRrgCJ
**CPU** | [AMD FX-6350 3.9GHz 6-Core Processor](http://pcpartpicker.com/part/amd-cpu-fd6350frhkbox) | $114.99 @ Amazon
**Motherboard** | [ASRock 970 Extreme3 R2.0 ATX AM3+ Motherboard](http://pcpartpicker.com/part/asrock-motherboard-970extreme3r20) | $59.99 @ Micro Center
**Storage** | [Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive](http://pcpartpicker.com/part/western-digital-internal-hard-drive-wd10ezex) | $54.98 @ OutletPC
**Video Card** | [XFX Radeon R9 280 3GB Black Edition Double Dissipation Video Card](http://pcpartpicker.com/part/xfx-video-card-r9280atdbd) | $194.99 @ Newegg
**Case** | [Rosewill Galaxy-03 ATX Mid Tower Case](http://pcpartpicker.com/part/rosewill-case-galaxy03) | $34.00 @ Newegg
**Power Supply** | [EVGA 500W 80+ Bronze Certified ATX Power Supply](http://pcpartpicker.com/part/evga-power-supply-100b10500kr) | $32.99 @ NCIX US
**Optical Drive** | [Asus DRW-24B1ST/BLK/B/AS DVD/CD Writer](http://pcpartpicker.com/part/asus-optical-drive-drw24b1stblkbas) | $16.99 @ Newegg
**Operating System** | [Microsoft Windows 8.1 (OEM) (64-bit)](http://pcpartpicker.com/part/microsoft-os-wn700615) | $89.98 @ OutletPC
| | **Total**
| Prices include shipping, taxes, and discounts when available | $598.91
A little room left for a CPU cooler if you want to overclock, and/or an SSD if you want that as well.