What's the best OSX book to get?

Just after opinions on books about OS X, as both myself and my father got a 12" PowerBook at the same time. Whilst I pick up new interfaces etc fairly quickly, I think a book would help for those special tricks that make things so much faster (I know just about all of them for Windoze) and I find a good book much more informative and easy to read that some ad-filled website with a separate link for every "tip" they deem appropriate to include. As for my dad, he's so lost in the "mount a disk image" idea and application "shortcuts" really being containers and would benefit greatly from a book to explain this compared with my feeble attempts.

The O'Reilly pocketbook on OS X seems like a nice, well-priced option by a reputable publisher, but some of the larger books also seem good. So I'm looking for any "you must get THIS book" type ideas

I'd suggest Mac OS X: The Missing Manual by David Pogue for your dad, and maybe one of the O'Reilly books for yourself. The O'Reilleys tend to be better for the "power user" types, but might be over your dad's head.

I'd like to add Dr Mac's (Bob Levitus) The OS X Files It's a very concise book