Another good one is PE5 for Digital Photographers by Scott Kelby. It's my bible - it sits by the side of the computer and is referred to often! What I like about it is that it's set up according to the most common features - correcting exposure, whitening teeth or making eyes sparkle are just a few examples. He walks you through, step by step, in very easy to understand language. This book won't get you into the finer details of using all the features of PE, but it's a great start.