Howtoforge posted a guide about installing Apache2 with PHP5 and MySQL support on CentOS 5.3
>> Installing Apache2 With PHP5 And MySQL Support On CentOS 5.3 (LAMP)
LAMP is short for Linux, Apache, MySQL, PHP. This tutorial shows how you can install an Apache2 webserver on a CentOS 5.3 server with PHP5 support (mod_php) and MySQL support.
>> Installing Apache2 With PHP5 And MySQL Support On CentOS 5.3 (LAMP)