OK, first read all the comments that people gave with that driver. They have a variety of suggestions.
One suggestion depended upon whether the graphics memory is DDR2 or DDR3. The answer might be as simple as adding 2 lines to the file: /Extra/com.apple.Boot.plist. Open that file in TextEdit and add these 2 lines:
Reboot the computer to see if that helped.
The driver you asked about contains two files called enablers that both do the same thing, just sometimes one works better than the other. Unzip the file and you will find a folder containing 3 files: Natit, NVEnabler64 and a Read me. I would suggest trying Natit first. Just double-click on the installer to install it. Then reboot your computer. If it doesn't work, you can try the NVEnabler64 but first you should remove Natit. Go to /System/Library/Extensions and find Natit.kext and drag it to the Trash. You will be asked for your password. Afterward, you can install NVEnabler64 by double-clicking the installer and then rebooting your computer.