I just received Call of Duty 4 as a birthdaty present from my son. Problem is that it requires Radeon 9800Pro as a minimum. I have radeon 9600Pro, so it doesn't work on my machine. So...Time to upgrade!! Can I please get some thoughts on what you think would be today's "sweet spot" in AGP cards??
AGP cards are disappearing but you still have options. I have Nvidia Gainward 7800GS+ that is very nice (but it's rare, you'd probably have to get 7800GS). ATI has an AGP x1950. Those are the top AGP cards (maybe that will ever exist though there are rumors of Nvidia coming our with an 8000 series card). They are quite a bit more powerful than the 9800 Pro (which I had before the 7800GS+).
The previous poster is right that you may need a new power supply too for these.
Check out the Geforce 7600 AGP cards; the benchmark numbers from some of those are pretty close to the standard 7800GS, at least in the reviews I've looked at. I have a 7800GS and it's been pretty good so far but newer games are starting to make it struggle.
Also, the 9600 Pro should be able to run anything the 9800 Pro can, just slower; does the game actually refuse to run?
I got the PCIe version of the hd2600xt for about $95 including free shipping and including Valve's Black Box. It games a lot better than I expected (having purchased the card for theater, not games). The 7800GT was a great card in its day but it was bigger and took extra power to run. The 2600 is smaller, just as fast, and does not need extra power. Amazing!