Yeah no need for a dedicated GPU, an FM2 mobo and APU would work.. easily under $400 w/ everything.
CPU: AMD A4-4000 3.0GHz Dual-Core Processor ($43.67 @ OutletPC)
Motherboard: Gigabyte GA-F2A55M-HD2 Micro ATX FM2 Motherboard ($39.99 @ Newegg)
Memory: Patriot 4GB (1 x 4GB) DDR3-1600 Memory ($34.99 @ Newegg)
Storage: Western Digital Caviar Blue 160GB 3.5" 7200RPM Internal Hard Drive ($29.44 @ Amazon)
Case: Xion XON-560 MicroATX Mini Tower Case ($29.99 @ Newegg)
Power Supply: FSP Group 300W 80+ Certified Micro ATX Power Supply ($39.99 @ Mwave)
Optical Drive: LG GH24NSB0 DVD/CD Writer ($15.99 @ Microcenter)
Monitor: AOC E960SN 19.0" Monitor ($89.36 @ Mwave)
Total: $323.42
(Prices include shipping, taxes, and discounts...