I've been considering a tablet for note taking as well, seeing my major is maths it would be a hassle to type all those symbols with a keyboard. While I haven't used one for such purposes yet, it would be just as practical as a normal sheet of paper, except with some screens it just doesn't have the same feel to it.
As for specs, I am aware of only four tablets with dedicated graphics. The Toshiba M4, which is very expensive in comparison with the competition, but its 6600TE is decent. The Toshiba M200 with its 5200 GPU, which is outdated, and I'm not sure whether it comes dual layer DVD writer. The Acer C200 and C300 are similar in specification with some design difference, the C300 is a conventional convertible while the C200 is a bit more unusual. Both are powered by the 6200 TurboCache, and not really serious gaming machines.
In the end, tablets aren't designed for games. So dedicated graphics is hard to find, and when it exist, will be some entry level GPU.
Tablets are generally more expensive and worse equipped than their laptop siblings. If you're willing to give up on the dedicated graphics, the Toshiba R10/15 has decent specifications for an alright price. But be prepared to see prices above $2500 for tablets in Australia.