The dummies series will teach you exactly NOTHING about using *nix. About the only thing you'll get from them is a false sense of knowing what you're doing.
Go check out "Running Linux" published by O'Reilly publications. That would be a good starting place. And if you would like a copy of Linux go to http://www.linuxiso.org
. It could take ya a while to download depending on your connection speed.
But DO NOT WASTE YOUR MONEY on a Dummies book!!! When they say "Unix for dummies" they mean "Read this book if you are a complete idiot".
And FYI: I have a copy of "linux for dummies". Saw it for five bucks and figured what the hell. That is $5 that I'm never gonna get back. Hell, I don't even want to use it as a doorstop cause then people will know I own it.