Macs are indeed easy to learn, I've used one since I was 6, but learning all the intricacies of the system can be quite interesting and not so easy by yourself.
Although, there are a lot of free articles on the Internet about the OS, but it's not quite as handy as a fully-featured book
I would also suggest a David Pogue "Missing Manual" book. There is one for Snow Leopard available now, though I have the previous Leopard version.
It is very good for newcomers to Macs, and is also valuable for more experienced users who need updating on new features.
Can't go wrong with this I think.