I use a Intuos 2 on the desktop and keep an older something-or-other (older littler blue/gray one) in my laptop bag. I use the tablet for almost all my regular Windows navigating/whatever as well as drawing in Photoshop or Illustrator.
Two comments on picking a model:
1. Price is dictated by size, but bigger is not necessarily better. My Intuos' drawing area is around 8x6, so my hand movements are no different than drawing on a piece of paper or in a small sketchbook, which is what i'm accustomed to. so it works really well for me. If you're a big sketchbook type of person, bigger might be better. If you're concerned about drawing little details, don't forget that you can just zoom in in PS/AI.
2. Price is dictated by sensitivity level. I *have* noticed some line quality differences on the cheaper models (both in recording the curve of a line and the thickness of the line). Maybe it's a lack of smoothness that's only visible when you zoom way in, but it's there and might affect your decision.