Upgrade MySQL and PHP on RT server

Dear all,

 I have to upgrade both MySQL and PHP on the current running RT server.

My box is RHEL AS4, RT 3.6.0 with FastCGI, MySQL and PHP (the default from
AS4 installation).

 Please let me know if there is anything i have to be careful about

before doing the upgrade.

Thanks and Regards
Sujith Emmanuel