Go to the Device Manager and select the Display Adaptor tab. It will give you the option to uninstall the drivers. After uninstalling the drivers it will prompt you to restart.
After it restarts go into Safe Mode (do this by hitting F8 a few times during the boot sequence) and use
Driver Cleaner to wipe clean any remaining Nvidia drivers. Be sure to just get rid of the video card drivers not the Nforce drivers if your board has an Nvidia chipset (basically just scroll through the menu list in Driver Cleaner and just select the "nvidia" choice).
After wiping the nvidia drivers, empty your Recycle Bin, reboot into Windows normally, and install whatever drivers you choose.
Edit: Beat me to the punch.