I unzip the drivers to a known folder.
I then simply go to C:\Windows\inf. In that folder I locate the nv3.inf and the nv4.inf and rename them nv3.i_f and nv4.i_f. I then go to Add/Remmove programs and uninstall the XP Nvidia drivers including the remove registry entries when asked.
I reboot, letting XP discover new hardware. When the wizard comes up, I lead it to the new drivers folder. The rest is a snap following instructions. Reboot, and use your favorite "tweak" utility to re-tweak your new drivers.
I then return the nv4.i_f and nv3.i_f to their original names incase of a problem windows will still install the default XP drivers.