Re: linux-2.6.31-13-generic +nvidia driver = black screen:-/
Boot to a Live CD once to the desktop launch nautilus as root. Browse to etc > X11 and locate the xorg.conf file. Open it and change the "driver" section under Device to nv instead of nvidia. This will probably be the only entry in the conf file as the newer version of X only use the file if it is there.
After that you should be able to boot to the desktop of your install.
Then add the nvidia-vdpau PPA here.
Then install the latest Beta driver with
sudo apt-get install nvidia-glx-190
This should remove all old instances of the drive as well. Then cross your fingers and reboot.
Running just fine with the good ole' beta driver here.
Dell Latitude E6510/Intel Core i5 M540
6GB DDR3/Nvidia Quadro NVS3100M 512MB[/I][/I]