When you ask for someone to set you up with an install of the latest CentOS, you’re still going to be stuck with an old version of PHP (version 5.1.6) which is missing many, many useful features, and includes a few bugs. Then salt is applied to the wound when you try to update PHP in yum and discover that 5.1.6 is the latest in their repository.

Here is a post that explains the easy way to update to PHP 5.2.x, without having to build from source.

http://www.freshblurbs.com/install-php-5-2-centos-5-2-using-yum

It relies on this third party Yum repository that contains a more up-to-date version of PHP and its extensions.
http://www.jasonlitka.com/yum-repository/