nVidia says that you should uninstall all display drivers before you install new drivers. So, that step was correct (intentional or not). Next, reboot. When your system comes back up you'll get a real crappy display (that's normal). Install your new drivers (nVidia has new ones for GeForce cards). I've never done it in safe mode, so I don't know what is normal with that approach.
"Driver Installation Hints" from nVidia
http://www.nvidia.com/object/driver_...ion_hints.html
Newest GeForce drivers for the Ti 4200 (56.72)
http://www.nvidia.com/object/winxp_2k_56.72