can anybody tell me a good book to learn the basics of cs4?
Oh my, with a professional application like CS4 there really aren't any basics.
Seriously though, I've worked my way through 3 of them at various times. One I fell asleep with (far too deep (although v.good) for my needs and this was 'Adobe CS4 for Photographers'
by Martin Evening. The second, well the least said about this the better - a book by Scott Kelby but as it's long since now on the refuge tip I can't recall the title anymore. The third book 'Adobe Photoshop CS4 - Classroom in a Book'
by non other than Adobe Systems themselves was probably the best of all and I can highly recommend it. Also comes with an accompanying DVD by the way.
I take it you do know that by going to the Help menu (when online) this will take you to the Adobe tutorial site