Lenovo IdeaCentre K230 5359-4PU for $469.99 shipped.  Here is a screenshot for your reference.  It comes with an Intel Core 2 Quad quad-core processor Q8200 at 2.33GHz, 6GB RAM, 640GB hard drive, dual layer DVD burner, Intel GMA 3100 graphics, TV tuner, wireless 802.11b/g, Gigabit Ethernet, Windows Vista Home Premium 64-bit, and more.  Note it is also eligible for Free Windows 7 Upgrade.  Most places have this system for about $599 or more without the wireless card and the TV tuner.