Problem is, once you install the nvidia drivers, MS completely forgets about theirs and there is no way to boot to tell XP to use them.
If you have a system backup, that would work but you would have to be able to activate it without XP whatsoever (can't boot to use systemrestore (don't know if that's required, since I never used it)). Booting into the LAST GOOD CONFIG won't work because the last time it worked was with the Nvidia drivers, which were removed by Driver Cleaner.
Reinstalling XP over itself would work, but I never advise installing OS's on top of eachother. And a format would take long enough you might as well do the method a described before, just to save on setup time.