The Tablet PCs are finally here. We’ve been hearing about them for years–small, light (some weigh less than 3 pounds) computers that you can write on as if they were a pad of paper or a personal digital assistant. These tiny powerhouses run a version of Windows XP, so you can use them like high-end notebook computers and run all your favorite applications. But you can also use them like virtually endless digital notebooks or sketchbooks, entering information with a special pen in environments where a desktop or notebook computer just won’t cut it. You can even talk to them.