Walmart offers the refurbished HP 6305 AMD A4 3.4GHz Small Form Factor Desktop PC, model no. WA2-0266, for $184 with free shipping. That's $24 off and the lowest total price we could find. Features include an AMD A4 5300B 3.4GHz dual-core processor, 8GB RAM, 2TB hard drive, DVD burner, Gigabit Ethernet, and Windows 7 Pro 64-Bit.
Note: A 1-year warranty applies although it's unclear who backs it.