MIddle of the road: PDA
I used to have a laptop from work, and although I was tempted, I never brought it to a game session. With all the books I carry in (I'm the DM, and it's starting to break my back) I don't have the energy for a laptop, too.
What I do have is a Handspring Visor Neo (palm pilot clone) and one of the folding keyboards that you can get for it. Add to that the word processing software I wanted for it, and I spent about $300 for the set -- not exactly chump change, and if I didn't want it for work and other things as well, I wouldn't have picked it up, but I have been bringing it to game sessions, and I've found that I like it a lot as a player, but not so much as a DM.
As a DM I'm always on the move -- shifting from one book to another, grabbing dice, moving minis, etc, and being latched on to a keyboard just doesn't work very well for me. I prefer the pen and paper (lots of index cards) to the palm. But in another campaign, where I am a player, I like the Visor as a tool very much. And all I'm using it for is to keep a log of our adventure. I could do that on paper, but I type faster, and it's a lot more legible than my handwriting when I'm trying to keep up with a verbal game. My notes are still a mess, of course, but they're a lot more complete, and a lot easier to sort out. And, they take up a lot less table space than laptops, and don't interfer with the line of sight to other players.
Of course, it's not really worth it if you can't swing the folding keyboard to go with the PDA. You'll never be able to input text fast enough using a stylus to take decent game notes.
-rg