You'll have to go get a PCI video card. Not all PCs have AGP slots.
I recently purchased a ATI RADEON 9250 128MB 128 MB VIDEO CARD. The instructions call for installation into an AGP slot, but I only have PCI slots on my Dell Dimension L866R. It does not appear that I have an appropriate slot for the card, unless I'm incorrect. Any ideas which will allow me to use this card in my computer? I'd appreciate any help you could offer.