Despite that this thread is from 2005, it is a very valid question, and I am very very much looking for the answer myself. Handling my linux based server without a control panel, and trying to learn it all, I could really use a book for beginner system administrators.
So far I have been relying on experience, trial and error, and tips from friends. But this does not give me a heads up if something is about to go wrong, or the knowledge to know where to look in order to fix it.
I will look into the above recommended book (thanks Martin!) but I hope more people might post a few more suggestions.