Asus CM1831-US-2AB Desktop PC for $499.99 shipped.  Here is a screenshot for your reference.  It features an AMD 6-core Bulldozer FX6120 CPU at 3.5GHz, 8GB DDR3 RAM, 1TB hard drive, 802.11b/g/n wireless, gigabit ethernet, dual layer DVD burner, Windows 7 Home Premium (64-bit), and more.  Most places have it for about $599.