HP Pavilion p7-1240 Desktop PC for $499.99 shipped.  Here is a screenshot for your reference.  It has the newly released AMD Trinity quad-core A10-5700 CPU at 3.4GHz, 10GB DDR3 RAM, 1TB 7200RPM hard drive, AMD Radeon 7660D discrete graphics, wireless 802.11b/g/n connectivity, and more.  Most places have it for about $599.