A really, really useful tool for capturing strcutured data and note taking is TreePad, by FreeByte Software. (They also have a really horrible website.) The freeware edition is awesome - it's basically just notepad with a treeview, and I like it much better than say OneNote (but I don't have a tablet PC) - you can have hyperlinks, and the automatic paste feature is great for harvesting content as you go along.
Wierdly, the full featured, please-buy-me version suffers terribly from feature bloat, and is so packed with crap as to be nearly unusable. I wonder if I can pay them for the free version?