Taking notes? I still have a web server running on one of mine :)
The sad truth is that it probably wasn't until the past year or two that PDAs/net-tablets caught up to what the Newton had in '97. It was definitely ahead of its time, but I was sorely disappointed to wait almost a decade to see just how far ahead of its time those little boxes really were.
Apple made a tablet PC in 1989, the Newton. It was attractive, but never really took off. http://en.wikipedia.org/wiki/Apple_Newton
Microsoft had a Windows XP Tablet PC Edition, which likewise went nowhere.
Typing is simply a better technology than writing, for text entry.