This would be decent. You are asking a lot though for only $400.
PCPartPicker part list:
http://pcpartpicker.com/p/3JyEa
Price breakdown by merchant: http://pcpartpicker.com/p/3JyEa/by_merchant/
Benchmarks: http://pcpartpicker.com/p/3JyEa/benchmarks/
CPU: AMD A10-7700K 3.4GHz Quad-Core Processor ($149.99 @ Amazon)
Motherboard: Gigabyte GA-F2A88XM-D3H Micro ATX FM2+ Motherboard ($64.99 @ Amazon)
Memory: G.Skill Ripjaws Series 4GB (2 x 2GB) DDR3-2000 Memory ($49.99 @ Newegg)
Storage: Hitachi Ultrastar 1TB 3.5" 7200RPM Internal Hard Drive ($49.99 @ Amazon)
Case: Cougar Solution (Black) ATX Mid Tower Case ($37.99 @ Mwave)
Power Supply: SeaSonic 350W 80+ Bronze Certified ATX Power Supply ($41.99 @ Mwave)
Total: $394.94
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-05-13 21:22 EDT-0400)