I've been using Tablet PC (Toshiba - portege 3505) for about 2 years now.
If you are getting Tablet PC - I really recommend getting a hybrid (basically it's a laptop but if you swivel the screen, it becomes a tablet PC).
Battery power on Toshiba and tablet PCs are not that great, hopefully newer models are better.
As for softwares, there are not many choices out there.
Most of the times, I use MS Windows Journal for my sketching, but I have used sketching software from Corel and Alias. But for designing flow diagrams and simple wireframes, windows journal will do the job (plus it's free).
I have tried using Tablet PC as replacement for building prototypes in paper. However, there were some problems during the usability testing. It was hard for me to share the same table pc screen with the user - unless you are directly in front of the screen, it will cause a major glare.
Another software I could recommend is Microsoft OneNote ( I believe Toshiba bundles this software when your purchase new Tablet PC). OneNote is a note taking tool, but it has capability of recording audio and synchronizing it with the notes you take. I found this software very useful when I'm interviewing users.
Hope this helps.
------------- original message -------------------------------------------------
From: Andrew Schechterman <aschechterman at yahoo.com>
Subject: [ID Discuss] Tablet-based PC's - ?
I'm exploring the purchase of a tablet-based PC for
doing sketching, prototyping, and more. A range of
models are out there such as:
Initial impression is the hardware/software technology
is still new (e.g., difficulties in saving free-hand
drawings to other formats? converting? other glitches?
Can anyone advise me on this? A good experience with a
certain model(s)? Software? Other impressions?