I've been using Ubuntu linux for a nearly six months now... As of last month, I've been using it exclusively while at home. This is a small collection of the things I've learned.
This one I kinda stayed away from for my first couple weeks... I have a tendency to be stubborn and try to do everything myself. Boy was that a mistake! Automatix has been rapidly improving since the release of Dapper Drake (the latest version of Ubuntu) and it's definitely the easiest way to get all those not-quite-free programs and other things that most people don't know exist. Get it here. The instructions are fairly detailed and right on the front page. One thing though... don't install everything unless you're sure what it is. Trust me. ;D
If you have a modern graphics card and you want your desktop to flow, you need XGL/Compiz.