Accessing the Internet with wi-fi (and wardriving): PDA or Nokia N800?

Hi, I'd like to buy a small, portable device to access the Internet when I'm on the street (I have a laptop, but it's too big to be used on the move...), and possibly to do wardriving (using Kismet and/or airomon-ng). In your opinion, is it better to take a Nokia N800 or a PDA? Are Nokia N800 expandable? I mean, can you put a CF card to make it a GSM/UMTS phone? As I see it, here are the Pros and the cons of each choice: Is the Nokia N800 much heavier than a standard PDA? Thanks a lot