What kind of computing background are you coming from? If you are a Microsoft Windows user, then Ubuntu, and KUbuntu are great options. Mandriva 2007, is a good one as well. If you go the Mandriva route, I definitely suggest going with the 2007 version. 2006, was known to be problematic.
Also with Mandriva, if you install the Documentation package, you will have a broad resource for a large variety of things relating to Linux. It's mostly older stuff, but may be of value. Ubuntu may have this as well, but I cannot say for sure, as I do not have a lot of experience with it.
There are thousands of resources for information, but it's hard to point you in the right direction, without knowing what you are looking for. Google is a great place to start, you just have to ask the right question.