I'm considering the same thing -- I'm preparing for a new small project and it seems like the perfect time to shed my reliance upon tables and go whole hog with CSS. But it would be really great to have a resource aimed at making that switch in a timely manner.
Reading specs don't help me for some reason -- I need something angled slightly different. I've been looking for such a book, but haven't found one so far.
Mostly, I read this forum's library, and print out anything really helpful. If I can't find what I'm looking for, and a quick search doesn't bring up somewhere else's article or column or forum post that I can print out, I ask about it in here. If I ask my questions clearly and ask appropriately for clarification, I easily find out what I need to know. Then, I print that out. I have quite a nice textbook by now. Nice and fat and comprehensive.
Could be a bit better-organized, but I can't ask for better-informed.
I still don't know much, but I feel I've got a world-class source for what I do know, and I feel like I could find out anything I needed to.