I'm now using a Lenovo Thinkpad X61 Tablet as my main computer at school. So far, I like it a lot. I'm dual booting Windows XP and Kubuntu 8.04. I was able to get the tablet functionality working, with automatic screen rotation (nifty!), using information on the following web page:
You have to have the "hdaps_ec" module loaded. I put it in my /etc/modules file.
You also have to edit /etc/X11/xorg.conf. Here's a link to the one I'm using (caveat emptor):
forgot to include the utility that calibrates it. However, it works acceptably. I used the Xournal program to jot some notes, and while it's not exactly like writing on paper, it's not bad at all. I may try to use this in class rather than writing on the whiteboard.