Hi. I am to this site (it is incredible!!) and was scanning through some of the threads and saw this one. I am a graphic designer (back in art school now to get my B.A. degree in design) and have the 6" x 8" Intous now. I had a smaller Graphire for several years.
The main difference between the Graphire and Intuos is that the Intuos gives you a lot more options as far as your stylus settings. You can adjust how thick or thin your lines are, you can adjust how heavy or light the paint flow is. I personally have not played around a whole lot with the settings on this yet (I've had it for about 3 months), but it does offer some options that the Graphire doesn't have. It also comes with a much nicer ergonomic stylus.
One thing I have found is that I usually change my paint flow and line weight through Photoshop so the settings on the Intuos aren't that important.
Either type of tablet is nice. One thing I do strongly advise is to get the bigger one of either tablet. You have more working room. Size does matter. With my smaller 4x5 Graphire, I was always running out of room. I have the 6x8 Intuos and it is a perfect size for me. It fits nicely on my desk and I have all of the room I need to work on my project.
Hope this helps some.
Judy