I helped a friend install Leopard on his G4 PowerBook. That machine has dedicated keys for volume up and down (F4, F5). Now with Leopard, those keys don't work. We tried going into System Preferences > Keyboard Shortcuts and tried to add Volume keys for iTunes. We added F9 and F10. They do show up in iTunes > Controls as an option, but don't work. They trigger Expose. So we disabled Expose and still, F9 and F10 don't do anything. So how do you get the volume up and down keys to work on an old PowerBook? I guess that same goes for the brightness keys too.