I'm not sure what you mean? When you install the newest version, it will update the necessary files for you. Do you mean any custom configurations/settings? If so, how many files do you have, other than a few (such as php.ini) that you might want to backup (though you probably don't need to).
well, i have zend optimizer installed on the server.
when i upgrade to the new version, that may cause a problem since my php.ini file has been reconfigured by the zendoptimizer installation.
also, when i first installed php, i did the manual install with the binaries and didn't use the installer version. all i did was create a folder called php, dumped the files in there, and configured httpd.conf and php.ini.
Slide a copy of your php.ini to php.ini.original Install/upgrade and then put depending on the changes, add the modifications in your original php.ini back in by hand to be on the safe side. Give yourself an hour of scheduled downtime for the first machine you do it on.
okay, i deleted the files and replaced then with the old one, made everything new except for the php.ini. i just tossed the old one back in. everything seems to be working now. i guess using the old php.ini wasn't an issue since there probably weren't much changes between 4.3.10 and 4.3.11