my powerbook keeps crashing, what is the best way to reformat a mac?

Boot from the 10.3 disc by holding the C key down. When you see the Installer window, go up to the Installer Menu to Disk Utility and use that to reformat the drive.

That is a good suggestion but then he'll have nothing on the drive to run from. If you boot from the OS CD as described above you can continue through the installer script and when the icon of your hard drive appears there should be an "options" button in the lower left corner. Click this and you will be presented with three options. The "clean install" choice (the one you should select here) will erase the entire hard drive and reinstall your operating system only. The "archive and install" option, specifically with the "preserve user settings and accounts" (or something like that) selected will leave your users folder(s) alone and just reinstall the OS. The third option I have never used as I like to clean out my OS level folders with the archive and install each time I get a new OS but you can choose to "upgrade" from a previous version and that will only install the needed files. Good luck!