Thanks Rob. I have a Bamboo Fun tablet, but don't have this problem. When I first got it, I did have problems with the drivers where if I picked up the pen far away from the tablet (say to put it down and use the mouse to do something or to type something with both hands), it would take several attempts (moving the pen up and down) to get GIMP to recognize the coordinates. After a week or two, I grabbed the latest drivers from the WACOM site and the problem was gone. When I got my new machine, I skipped the CD and got drivers from the WACOM site and have had no problems.
The only minor (well, sometimes major) annoyance is that when I unplug the tablet (since it's on a laptop I move around) and plug it back up, GIMP (even starting GIMP after plugging in the tablet) does not always recognize the tablet is installed and I have to shut down GIMP and run the tablet pen utility and start GIMP back up to get it recognized. The pen still works, but it's in "mouse" mode I guess, so pressure sensitivity and stuff don't work. I expect this has more to do with GIMP (possibly windows) than it does with the tablet.