http://en.wikipedia.org/wiki/.NET_Framework 

You can 'live without' almost everything....perhaps not food, water and air ....[not in that order of importance]...air comes first...then water...then food.

As for MS's net framework .... not if you 'do things' with your computer [other than look at it and say 'yes, it runs smooth'] ...

NET Framework is the basis upon which most Windows programs/apps are built.  If you do not have it installed many of those apps will not run, and in some cases, will not install at all.  So no, you cannot live without it, not if you want to install and run games, programs, apps.

Yeah, I know, it said that at the other end of Jafo's link.  I just wrote it for the lazy people who don't never click on feching links.

When updates to .NET are offered through the Windows Update Utility, it's generally good to note it's number and wait a couple of weeks and watch the tech blogs regarding problems with it.

The thing is, I cannot recall a NET update causing me problems... No Shit!

Guess I'm one of the lucky ones.. touch wood.