Tablet PC advice


So I am thinking of buying a Laptop. And the bottom line is that I want to get the most bang for my buck. My main idea is that I want a MAC (because they rock as laptops). But. . .

I want to be able to take my design on the road, go outside, do stuff like that so I and less constrained by a rigid desk and a my cold, unfeeling chair. I am looking into tablet PC’s because I know that working on a tablet is wonderful. Yet I have not been able to afford one yet. So it is either buy a laptop (MAC) and a tablet for my PC or get a tablet notebook. Thus, any thoughts on this matter would be much appreciated.

(tablet PC’s)What brands are good, what should I look for, good prices etc…

Should I go the mac route and just buy a tablet for my PC?

or should I just buy myself a nicer chair:P