Dunno about the existance of a graphical tablet with buildin screen... (or maybe that is what a tablet PC is
), but the graphical tablets usually detect the pen position even before it touches the tablet. Thus your mouse on the screen moves accordingly (that is, if you have a decent graphics tablet and pen).
Still, it is indeed something you need to get used to to be able to work properly with it though... It is very ackward the first time you use it. The reason being, I think, is that if we write or draw something on paper, we all look at what we're writing or drawing. With a graphical tablet you shouldn't do that, instead you need to look at your screen while you are drawing, which is very unnatural.
It is like a mix between using a mouse and looking at the screen (we are all used to that) and drawing on paper and looking at the paper and pen (which we are also used to do without even thinking about it)...
Indeed, the reason why I only used a graphical tablet for a short while was exactly because the novelity wears of pretty quickly. It is cool to use it to draw your autograph or something, but if you're not a true designer or something there isn't much/frequent use for it...
But, I would be extremely happy if someone gives me one as a present, that's for sure (it is afterall a cool thing, and sometimes usefull, to have... compared to other gadgets!)
all IMHO of course...