[Crass]

Depending on what you're using to draw with I really wouldn't recommend using GIMP. I don't know if it's been updated to accommodate tablets or not but in my past experience in the digital art world it's lacked the pressure sensitivity required for smooth lines and gradients.

If you can get your hands on a free cope (non-trial) version of SAI, do it. It is a very straight forward program and it's works with most tablets.