Pocket PCs do a lot more. If you want to do a lot with it, get one of those. That's what I did.
However, if all you want is a scheduler, address book, and basic stuff like that, I would suggest something cheap, pocket pc or palm.
Think about how you will use it. Only the smallest models on the market are really worth carrying in a pocket, especially if you already carry a cell phone. Just be sure to research it thorougly before you decide on one.
This is the one I got:
http://www.pdabuyersguide.com/ipaq_2215.htm