I have just acquired a hp tc1100 tablet and am happily using ubuntu on it. It does require a fair bit of configuration though.
1) ubuntu now comes with xorg auto configuration, you need to undo that and write a custom xorg.conf to include tablet support (plenty of guides out there)
2) you need to modify
3) get cellwriter and train it, it's good and comes with an integrated OSK
4) configure your drivers to support RandR and use the script here http://www.thinkwiki.org/wiki/Wacom_Serial_Tablet_PC_Stylus to enable rotation between portrait and landscape mode
5) if you are using intrepid and have nvidia hardware, nvidia binary blob drivers will not work yet (nvidia has not updated for new xorg yet)
6) xournal is easily comparable to windows journal but requires a bit of fiddling to get the preferences just right. Also, it has drawing problems if you set your zoom level to anything BELOW fit to width
7) I use opera for browsing as the sidepane menu is so versatile. Also, it supports drag scrolling by setting the about:config options "scroll is drag"
8) evince unfortunately only supports drag scrolling using the middle mouse button and does not offer any way of configuring that. (bugs have been submitted though)
Gravity is a myth, the Earth sucks.