Warning: this procedure WILL erase EVERYTHING on the iPod. Do it at your own risk, I accept no responsibility.
Plug the iPod into your powerbook. Go to your /Applications/Utilities/iPod Software Updater folder and open the most recent updater software in there. There are two buttons if I remember correctly: "Update" and "Restore." Update places the most recent software on your ipod leaving everything intact. "Restore" is what you want; it'll erase the entire iPod, all its contents, and format it for the computer its attached to.
Make sure you back up any important music or data, and use this at your own risk.