Review from mcitpworld.com:
If personally or professionally you'll be upgrading to Office 2007 and you expect to use PowerPoint for your presentations, you'll need "The book that should have been in the box". "PowerPoint 2007: The Missing Manual" will show you how to work all the new knobs and buttons. Buy this book and you'll be an expert in no time.
http://books.google.com.my/books?id=HVnGLL0nBzEC&printsec=frontcover&dq=powerpoint+2007
I think this one is worth it!