The nVidia website lists driver version 169.21 as the latest and greatest for your card. I don't know if you are using the one from Microsoft. You might try going to nVidias site and getting their driver.
I read the documentation on it and it seems to support numerous screen resolutions.
Here's the link
http://www.nvidia.com/object/winxp_169.21_whql.html have a read of the documentation and try it. It might help.
Good luck