Mike McGrath's Linux in Easy Steps is recommended beginner reading and preparation before venturing into the world of Linux.

It offers a great overview and insight into; how to get started, Linux architecture and common applications usage, and it is packed with plenty of cool tips and tricks. It also has the added bonus that it's free of technical jargon, and that will make the transition to Linux that much smoother and a less painful experience!

My only negative criticism is that the author primarily focuses on the Suse Linux distribution. But having said that, what you learn here can easily be applied to other distros.