No, in fact if you simply set up your new PDA with the same HotSync username as your old one your serial number will still work. This is easy to do - just uninstall the old Palm Desktop software, including its associated user data (it'll ask if you want to delete that), from your computer, then install the new version of Palm Desktop that comes with your new PDA and you can set it up with the same username as your old PDA the first time you HotSync.