Might want to look here:
http://www.thinkwiki.org/wiki/Category:X61_Tablet
I had the X61 tablet. Mine didn't have the option to move stuff with your fingers, only the stylus. The problem with GNU is that some programs are written with KDE/QT and some with gnome, so you are not going to have something that's just KDE like I prefer. I never installed Slackware on it, but I did put Arch on it and it was running great. The tablet part not so much, since you have to configure the screen rotation and the screen orientation buttons with scripts so that they will work, even on Ubuntu.
It's been a while since I have had the tablet though. Things are always improving. As a notebook, true thinkpads (X, T) are great. I dropped this thing from a bench and no harm done, the keyboard and mouse nub are a joy to use. I would not recommend any other notebook but Lenovo Thinkpads, for anyone. As a tablet, I would recommend going Android. A thinkpad tablet just came out that uses Android and you can use either stylus or your hand. Or read the reviews for the X220t, which gets better battery life. My X61 got 4-5 hours.