Hey, I had the same problem. Here is what I did to fix my performance problems:
1. Get RivaTuner:
http://www.guru3d.com/files/rivatuner/
2. Ensure you have the lasted Nvidia drivers.
3 Update your AGP driver should haven't already done so.
4. Extract RivaTuner into its own folder, then run it.
5. Go to the PowerUser tab, disregard the warning, then look at the bottom for the folder icons. You want the second one from the left which when selected displays "Open matched Detonator database." Click it.
6. Once it loads, find the fifth line, it should say, "NVIDIA Detonator 29.4x w2k(even if you have XP) System."
7. Once found, scroll down to "Enable Ali AGP." Right click it, click the lighted bulb, and make sure that "1" appeared in the right-hand "Value" column. Exit RivaTuner and reboot.
8.Once rebooted, initate a directx diagnostic and you should find that you can enable the AGP texture acceleration.
I can now run NBA Live 2003 at 1024 res full details with aniso enabled and its smooth as hell. It also boosted my 3dmark score from 5000 to 7500!