Hey BIC! I haven't read any of these myself but I looked at the info on Amazon to form my opinions. Hopefully it's a little helpful to you.
Adobe Photoshop CS2 For Dummies - Looks like a pretty good one for a first-time user. It discusses how to use some key tools and also some of the more fun things. And those "for Dummies" books are usually written clearly and easy to understand.
$16.49 new
at Amazon.
Adobe Photoshop CS2 On Demand - I can't find as much information online about this one. Not as many reviews on Amazon either. The description isn't very thorough and I can't "look inside" it. Judging by the description it looks like it might be pretty basic, though.
$23.09 new
at Amazon.
Adobe Photoshop CS2 for the Web... - Seems like this one is packed with tutorials (over 100) but they look really technical. Not exactly basic and I don't know if it's what you're wanting to learn right now. To me this seems like more of a learning tool for a designer. It has a lot of how-tos for integreting other Adobe programs like Illustrator, Flash, and Dreamweaver.
$32.99 new
at Amazon.
Adobe Photoshop CS2 One-on-One - This one claims to be good for beginner and intermediate CS2 users. I don't see very many specific tools and topics that it discusses though. It sounds like it might be an easy read too, hopefully not too technical.
$26.37 new
at Amazon.
Adobe Photoshop CS2 Classroom in a Book - This one looks like it covers everything from the basics to the fairly complex. Lots and lots of good reviews from other users too. I couldn't look inside on this one so I can't tell if there are many good visuals or not. The quizzes at the end of the chapters could be helpful to you. If you want to have something that will continue to help you as you advance this might be a good one.
$32.99 new
at Amazon.
If you get a chance to, go to a Barnes and Noble or a bookstore that has books like these and take a peek before you buy. Check to see if they have plenty of visuals to help you along the way. There's nothing worse than being in the middle of a tutorial and only having a block of text as your guide. Samples and visuals help many people remember things easier too.
Personally (and I think this goes for a lot of others) I've learned the most about Photoshop by just messing around. It doesn't hurt to have a book or two around to guide and inspire you though. I find tutorials from the web to be pretty useful learning tools as well.
Hope that helped you a bit!
Mars