This might be helpful Rekubot.

http://en.wikipedia.org/wiki/Radeon_X600#New_interface

You should be able to tell upon startup.. right click on the desktop - goto properties, then settings, then advanced. It should tell you there. The radeon X600 series did come in AGP and PCI express formats. You are hopefully lucky enough to have the pci express version - if so, then you should have absolutely no worries when it comes to upgrading - if not, you'll have to spend more money, and your upgrade options are far more limited.

Location: PCI Slot 10 (PCI bus 1, device 0, function 0)

Looks like I'm lucky . Thanks a lot, Razorpig.

Thanks for the link Darth. It says those cards are pretty popular with the Dell Series, which I have, go figure . Now all I have to do is figure out which one I'm going to get, and there's more than enough suggestions in here. Thanks guys!