Upgrading PHP with RedHat and Ensim 3

I have a dedicated server that runs redhat and ensim3 webpliannce.  The PHP version is 4.1.1, and I need functions available in 4.3.

I'm scared to death to upgrade it.  I don't have any idea about the dependencies that Ensim may have on PHP - it might be a PHP app for all I know.  I do know that when I ran:

# rpm -qa | grep php

I got:

php-sysvsem-4.1.1-4ensim3
webppliance-mod_php-frontend-3.1.0-25
php-snmp-4.1.1-4ensim3
php-4.1.1-4ensim3
php-ldap-4.1.1-4ensim3
php-pgsql-4.1.1-4ensim3
php-devel-4.1.1-4ensim3
php-sysvshm-4.1.1-4ensim3
phpMyAdmin-2.2.0-ensim4
php-imap-4.1.1-4ensim3
php-mysql-4.1.1-4ensim3
php-ftp-4.1.1-4ensim3
php-gettext-4.1.1-4ensim3
php-manual-4.1.1-4ensim3
webppliance-mod_php-3.1.0-25

I don't know if this means that the version of PHP 4.1.1 is somehow bespoke to ensim, or if it is just naming used by ensim when installing PHP.  I'm seriously considering starting over on a fresh server and then migrating the sites.

I'm looking for guidance from the experts...

cheers,