Before you pick any of them, take a good look at your desk and think about the real dimensions of the tablet - I have an Intuos 3 6x8 inch tablet, and while it's a great tablet, the thing is huge, it's nearly as wide as the keyboard because there's a lot of surface on both sides that isn't part of the actual drawing surface.  If you mean to hold it in your lap or have some way to just place it conveniently (which I don't, not really) then it's a great tablet - think about getting a smaller one though, they really don't have to be all that big.  It depends a lot on your stroke style too, whether you draw with your whole arm or mostly small motions of the fingers and wrist.

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