Hi dave try Google.

Basically you want to have a Quadro AGP card, but the good ones are quite expensive even for AGP and (correct me if I am wrong)since you still own an AGP based machine budget is a bit tight(not an insult), that's prob out of the question.
My advice to you is if you have an AGP card already just run along with that one save some money to buy a new rig which is PCI-e powered, if that's possible.
If you need an AGP card buy an NVidia game card that is AGP with reasonable specs not to high end and to high prized.

Even if you have the money don't be foolish don't invest in ancient technology which is dying out.