These are the php packages in testing
http://dev.centos.org/centos/5/testing/i386/RPMS/
php-5.2.3-3.el5s2.i386.rpm
php-5.2.6-2.el5s2.i386.rpm
php-5.2.9-2.el5.centos.i386.rpm
php-5.2.10-1.el5.centos.i386.rpm
enabled=0 : Means disabled.
Please edit to : enabled=1
( Suggest : Change it back to enabled=0 , when you have installed the all required php* ).
..