If you've decided on Debian/Ubuntu Linux as your distribution and you're not already a Linux expert then do yourself justice and purchase a copy of this book. It's thorough and comprehensive; all the while it's insightful and intriguing. The author does a competent job fleshing out concepts while not drowning the reader in distribution specific jargon (which is a real weakness in some Linux texts). The chapters are logically structured working up to more advanced topics and the author never insults the readers intelligence.
I have used Unix/Linux off and on since 1999 and this book brought me back over to Linux. I've never been a particularly advanced user and I always hated searching online for hours trying to figure out how to do things in Linux. Now I just reference this book, which remains on my desk at all times. This is THE book to own for ordinary users and systems administrators alike.