Keep the OS (Operating System) up to date for your handheld is the best way to make sure you are abreast of the latest patches to address issues as well as security. Palm has patches available here for most models.
Note that you cannot change the OS to a primary version other than the one your handheld was shipped with. For example if your handheld has OS version 3.2 you can upgrade to version 3.5 but CANNOT upgrade to versions 4.x.