I recently got ubuntu 12.10 x64, and while trying to install the drivers for my Nvidia GeForce GTX 460, I ran into trouble. I couldn't download the linux version off the site, and I tried running the directions listed here: Ubuntu 12.04 Nvidia GTX 460 video card installation. Neither of these have worked for me. Any tips or other commands a noob could try?
My suggestion would be to purge all the nvidia drivers and go with the open-source nouveau ones instead.
Enter your password when prompted, wait for the process to complete (prolly only a few mins) and reboot your PC.
Once rebooted, your nvidia drivers will be gone, replaced with nouveau.
I had many a trouble with proprietary nvidia drivers, but none since I changed.
Hope that helps.
Most people I have spoken to have had better luck installing the proprietary driver from nvidia. It's available at http://www.geforce.com/drivers I had to do it for my ION series card because the nouveau driver had no HDMI audio support for my card.