Adobe Photoshop CS5 for Photographers by Martin Evening.
I have others for CS3, but a friend of mine purchased this one and let me have a look at it. I immediately found a couple of things that I had been struggling with and a clear explanation of the specifics. It comes with a DVD with images from the book and I have ordered it for myself and am expecting it in a few days.
Where I am, there is a branch of the on-line store I ordered it from and they allow/encourage individuals to drop in and have a read - in Canada, it is Chapters. They also have a no quibble return policy if I change my mind - good for 14 days (I think), but I have never returned a book. ANd, oh yes, free shipping if above a price threshold - and this book qualifies, and even better, I can return it to the local store!
Can't beat that!