GeForce 8600 GT 256MB DDR3

i'd try booting in safe mode and see if it boots up
try "Enable low-resolution video" or "Enable VGA Mode" (depending on whether you have Windows XP or Vista)
try updating the drivers...
try taking the video card out, cleaning the PCIe connection w/ some caned air to get dust out
if that doesn't help than you've probably lost your card.

I'd honestly wait a month to get a new one, once the next generation of cards come out (DirectX 11) like Nvidias GT300 line.
Either get one of the new cards, or @ least the present generation cards will become cheaper