It's more a question of where it is, John. I assume you're talking about an independant card, rather than on board graphics? If that's the case, pop the side of your case off, and have a look to see where it's seated. If it's in a small brown slot, it's AGP. If it's in one of the white slots, possibly next to your modem or sound card (?), it's PCI, but if that's the case, have a look to see if there is an empty brown slot, above the PCI slots, towards the middle of the motherboard, in which case you could probably upgrade to AGP.