Deleting temp folder under local user in Vista - safe?

I am currently doing some lightweight cleaning of a friends computer and I was wondering what is safe to delete in the temp folder under user/appdata/local/temp?

Somehow he's managed to fill it with more than 100 gb (!) of stuff that I really see no need for but I'm afraid there might be something there that is required for the computer to keep running normally.

I've thought about creating a new user and just deleting the old one, is that a viable solution to the problem? If yes, what problems might occur then?

 

Click Start / run /type in %temp% and delete everything in there, if there's anything in there you can't delete it will give you the option to " Save Skip or Cancel " just click "Skip", these are files that cannot and will not allow you to delete them, that should do the trick !

 

Ok, but what about my suggestion to just replace the user account and delete the old one, is that a viable idea?

 

Alright, thanks guys I'll go try it now.