Installing X11
G4 Tower (still kickin'), iBook G4, 20GB iPod Mac OS X (10.3.9)
To install GIMP use the commandHope it works for you. Have not tried it myself. Just learning about this stuff.
sudo apt-get install gimp
If you run into problems using apt-get, try using
fink install gimp
as a workaround.
Installing X11