I have the same card as you but im on vista x64. Download the driver from nvidia web site : http://www.nvidia.com/object/winvista_x86_158.18.html
And make sure you uninstall the older driver of your last video card. It show on nvidia vista how to when you download the driver. Those are the last driver:
ForceWare Release 158
Release Date: April 26, 2007
DID this fix the problem i have the gigabyte 8600gt card. The install would time out half way through. I downloaded 158.18 and removed the previous card installed, then installed the driver successfully, on reboot ended up with a blue screen of death. Safe mode to remove.