http://www.nvidia.com/object/winxp_186.18_whql.htmlLatest drivers.
Also make sure you have the required version of DirectX installed and the latest patch for the game (if any).
Make sure you meet the minimum requirements as well:
* Supported OS: Microsoft Windows XP / Vista / Vista64
* Processor: Pentium 4 3.0GHz
* Memory: 1 GB
* Graphics: 128 MB, Shader model 2.0, ATI 9600, NVidia 6600 or better
* Hard Drive: At least 7.5 GB of free space
* Sound Card: DirectX 9.0c compatible sound card