this is gonna require you to open your case and take a glance inside at the slots on your motherboard. Look for what they're shaped like, most would look like regular PCI slots but especially in old motherboards there would be One special slot for video, they're either AGP or PCI express. look at the slot these parts would fit in.
This is your prime choice if its PCI Express
http://www.newegg.com/Product/Produc...82E16814134028
dont mind the tab, it is rated for PCI Express
If your still slackin with AGP like me...
Good luck
its really time to straight up buy a new pc, AGP is dead