Normally LMCE will do that for you. If it doesn't or the driver is wrong for your card you can do it from a command line or install Adept (see above) and type in nvidia to the search term. I will list all the available Ubuntu packages. Check them for the one correct for your card and install just that. It will automatically install any dependencies. I think the preferred one, nvidia-glx is automaticaly configured when you start LMCE but I have not tried it on the most recent versions.