Could be your motherboard drivers forcing the card to run in 1x or software mode. Go to your motherboard's webpage and get the latest drivers for the chipset if all else fails. This happened to me years ago when I was running a 9600. The drivers for the card were installed, but for some reason my motherboard was running the card without agp support.
You can check this by going to Display->Settings->Advanced and under one of the tabs there (I forget now, and can't check since I have a geforce 6600gt) should be an option for setting the AGP as well as fast write / read. If it's running at what it's supposed to 4x or 8x depending on your computer, then you don't need to update mobo drivers.