When installing Panther, click the "Options" button to choose an Archive Install in order to preserve a copy of the existing "System" folder before installing a fresh copy. Be sure to select the checkbox for preserving Users. At the cost of taking up more hard drive space, and the possibility of having to re-install certain software (anything that puts files in /System), you will end up with a cleaner-burning system. This is because the new OS is not merged with existing (and possibly problematic) system files, as it is with an Upgrade install (which is the normal installation method). If you are confident that your system is working optimally, an upgrade install is safe.