I have an old notebook that has 512MB of RAM. I put Ubuntu 10.10 Netbook on it. It works, but I can't install any packages or a simple web browser. What alternative versions of Ubuntu do I have that are more compatible with my notebook?
On such a "low-end" device I'd recommend Lubuntu. Lubuntu is a lightweight version of Ubuntu, using the LXDE desktop environment.
It is specificly designed to work on machines with low amounts of RAM, old CPU's and small harddrives.
Download it from http://lubuntu.net/ , burn a CD/DVD with it, and try it out in the Live session.