If anyone is interested in getting one last umph out of your AGP based box it can be done.
I have a back up machine with AGP that handles everything except Far Cry and Crysis. So it plays all the Battlefield series games and Team Fortress 2 very very nicely. And SOF2....and it should handle COD2 for sure.
You would need to find a BFG Nvidia 7800 GS OC. It has to be that card. I can overclock that card to run really really well.
The card will run you 200 but if you are already at say 2.5Ghz CPU or so and have or plan on having 2-3GB of RAM then it would be well worth it.
I have played that machine with quite a few excellent online games and no issues at all.
It does get hot so you would need a lot of fans and a nice case and 700 watt dual fan power supply.
For the 200 I spent when upgrading that machine for the last time it has been played on hard for 3 or 4 years by a ton of friends and myself.
I plan on getting at least another 3-5 years out of it still!