As far as quality goes, you have to get a wacom. Personally I have the 4x6" one, which is the smallest they do (cost me Ł45) and it's plenty big enough for most things. Ignore the cheaper brands - the quality is not nearly as good, and some have driver issues - some don't even support the macintosh platform which is madness for a graphic design tool (they're cutting out 60-70% of their audience). Mine came with tablet, pen, mouse (no mouse ball or optical sensor) and corel painter. Pretty good deal IMO
are two models you may be interested in.
I can control the entire Mac OS with the pen - using it as a keyboard and a mouse. Inkwell lets me write into almost any text box on the fly, and use gestures for things such as delete, enter, tab and so forth. Sadly, windows lacks this feature.