he said he had pci and agp slots. not a cpi-e slot. shoot for a 6600gt. theyre around 100 bux for cheapish ones, better ones are around 130.
it also depends on the speed of your agp slot. either 2x/4x or 4x/8x. if its a newer system, then most likely 4x/8x. older system are 2x/4x.
if you want a 6600gt, im selling mine in my sig VVV
list of agp 6600gt's at 4x/8x
http://www.newegg.com/Product/Produc...TTR18=&ATTR19=