If you install nvidia-glx-195 drivers from Nvidia Vdpau Team PPA then you may have trouble removing them later due to packaging failure ;) Actually, the problem will crop up when you try to reinstall nvidia-glx-185. I had to do this because my GT 240 is unsupported under all versions of the driver, and while it works it locks up hard on anything later than -185.
During the install of nvidia-glx-185 you will get errors regarding file diversions in GL libraries. Here is a fix.
for i in `dpkg-divert --list |grep nvidia|grep 195|cut -f3 -d' '` do sudo dpkg-divert --remove $i done
Now go forth and read manpages until this makes sense to you before pasting it into your shell!