You should choose a low-cost tabletop. Laptop… No, nononono. You get more for less if you go for a proper PC, with easier to fix insides if anything ever blows up, and the most important question: Are you going to chuck it around continuosly? If not, then don't go for a laptop.
(as a sidenote, my samsung N150 mini laptop runs nwn, with win 7, but I wouldn't go questing with it. Done some RP with it in school every now and then, though)