SteveW wrote:i am pretty sure it supports PCI
PCI is for add in accessory cards - not fast enough for video cards.
AGP goes 1x up to 8x with increasing speed.
PCIe 16x is faster again.
If you are nuts and rich and your mobo supports it you can run two video cards in parallel.
So, read your motherboard manual to find out what type of video slot it has then something like PC Authority or PC World for card reviews. Then get the fastest you can reasonable afford. Personally I prefer nVidia cards.
My older computer has AGP 8x, but newer machines like my latest tend to use PCIe - but remember that is vastly different from PCI.