It depends really. Hobbyists should stick with the Wacom Bamboo Fun (8x6). It's good for drawing, and it is very lightweight. The removable cord makes it able to place almost anywhere. It's only about $100 and it comes with software (Adobe Photoshop Elements, Corel Painter Essentials) if you don't have drawing software already installed. It has 512 levels of pressure sensitivity. It's pretty comfortable and easy to work with when you're a beginner.
I have the Wacom Intuos3 tablet (5x4), which is bigger and a bit heavier. It comes with the same software as Bamboo Fun, however it features 1024 pressures of sensitivity and Pen Tilt. I love my Intuos3 and my Bamboo fun for different reasons. I would definately get the Bamboo Fun if your budget is tight. Intuos3 is not much of a beginner's tablet. Intuos3 5x4 costs about $199. Bamboo Fun 8x6 costs about $99. The smaller the tablet space, the easier. On the computer I have, it's much easier to use a 8x6 or 5x4 than anything bigger. It just depends on how big your moniter is in the end.
If you don't like my suggestions, at least get a tablet from Wacom. They are excellent products, which gives you many discounts on big software, such as Adobe Photoshop and Corel Painter. I love using my tablet for many things. <3