NVIDIA drivers always leave the installer for each version you install in C:\NVIDIA\DisplayDriver\xxx\ (where "xxx" is the version number). When you install a different driver, select custom installation (untick HD Audio and 3D Vision unless you have those) and enable "Perform a clean installation", so it will completely uninstall the current drivers installed.
And, if you don't have any of these installers in your hard drive, go here:
http://www.geforce.com/drivers/beta-legacyIt should list older drivers based on the card and OS you choose.
By the way, in case you are using WSE2 and, since it now re-enables "load textures on demand" after every patch, check if that option is enabled. It causes a lot of stuttering for me.