you need to get into a PDA frame of mind. Some people find them totally useless, whilst others would rather have pins stuck in the eyes than lose their PDA.
I have one that picks up my email wirelessly, and I use it to carry the odd few files around on my travels if I don't fancy carting my laptop about. It's useful in a way, but to be brutally frank I think I still prefer my trusty Filofax. I know that's heresy coming from me, but it's true. I'll kill to keep my laptop, but my PDA hasn't really made my life that much easier......apart from the wireless email thing, and that's definitely worth having.
The problem with a PDA is that you can't actually jot down the odd note that easily - the onscreen keyboard is a tad fiddly, and the handwriting recognition is abysmal. Added to which you have to go through the faff of switching the thing on and off, dropping the stylus at the worst moments, and then finding that at a critical moment you get a low battery warning.
Really decent PDA = around £200 to £300
Really decent Filofax (personal size) = about £45
Now I'll fall on my sword.