ges and will leave
mysql-5.0-5.el5_9 in place for now. FYI, I searched through the rest of the installed packages, the only one that has the client library is mysql-5.0.95-5.el5_9.
php-mysql is linked against mysql-5.0-libs and talking to a mysql-5.5 server. Should this cause an unpredictable behavior?
No.
-- Eero