This is what I was going to pick initially but the Athlon X4 was cheaper so I went with it instead. This gives a decent upgrade path.
PCPartPicker part list:
http://pcpartpicker.com/p/3qXui
Price breakdown by merchant: http://pcpartpicker.com/p/3qXui/by_merchant/
Benchmarks: http://pcpartpicker.com/p/3qXui/benchmarks/
CPU: AMD Phenom II X4 955 Black 3.2GHz Quad-Core Processor ($91.98 @ SuperBiiz)
Motherboard: ASRock 960GM/U3S3 FX Micro ATX AM3+ Motherboard ($53.99 @ Newegg)
Memory: A-Data XPG V1.0 4GB (1 x 4GB) DDR3-1600 Memory ($31.99 @ Newegg)
Storage: Hitachi Ultrastar 1TB 3.5" 7200RPM Internal Hard Drive ($51.00 @ Amazon)
Video Card: PowerColor Radeon HD 7770 GHz Edition 1GB Video Card ($102.98 @ SuperBiiz)
Case: Silverstone PS08B (Black) MicroATX Mid Tower Case ($39.99 @ Amazon)
Power Supply: Corsair Builder 500W 80+ Bronze Certified ATX Power Supply ($49.99 @ Amazon)
Total: $421.92
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-04-13 09:50 EDT-0400)