Most new handhelds can do all of that and plenty more, so I would recommend you to get the cheapest handheld you can find with at least 8MB, or more. Ebay it if you really want something cheap.
I'm about halfway through medical school, and will be starting work in the hospitals this summer. Does anyone have any advice on the best handheld for me? I want it to run the programs I need--pharmacology info and be able to store medical textbooks--as well as have a great datebook feature.