It either Just Works or you're in for some pain as you google for somebody who had the same problem as you or try to get help on a forum. I had little trouble getting Ubuntu to work on the machine I'm using now, but I have had serious problems before.

I've been using linux since 2002 and things are getting better. With Ubuntu, your chances of throwing it at a random machine and having it Just Work aren't bad - but they're still far from certain.