I recently purchased a “starter” tablet, just to get used to it and to see if I really like it with out having to spend a few hundred dollars. I bought the regular bamboo (does not include a mouse) off of a dealer on amazon.com for under $60(with s&h) and I absolutely love it. It has a touch sensitive zoom ring on the top that I am constantly using no matter what app I am currently using. The only thing you sacrifice by using a wacom tablet in photoshop is the ability to paint a straight line via shift clicking like you would with a mouse.
The really nice feature of these things is that they are pressure sensitive, so you don’t have to constantly change your brush size, that feature alone saves a TON of time.
The bamboo also comes with a somewhat useful gestures program (on mac os and vista). You make specific moves with your pen and it performs an action universal to all programs (undo, redo, cut, paste, ect.)
I can barely function in photoshop without it anymore. It took me a couple days to get used to it, and probably a week or 2 for it to really become second nature for me. It’s obviously not the best, most sensitive, ect. but for under $60 it’s one of the best purchases I’ve made.