Depends on what kind. You DON'T have an AGP or PCI-E slot in that computer (technically, the AGP slot is used by the Intel graphics), only a regular PCI card. Best PCI card you could get for your machine is the 9250 which would run it about Medium depending on park size.
If you buy it, don't get it installed. It's really easy to just take the side of the case off, take the little case slot cover off, and then drop in the card. It takes at most 3 screws, and about 10 minutes (at the longest).