I have created the first customer and site in ISPConfig and now is working great... But it seems that the site is working with php 5.1.6 (that is the version that I have installed using yum in my centos) because that it what says phpinfo command executed from that first created site. I dont understand why is using this version, since I saw the php 5.2.5 compiling during the ISPConfig installation. So... What is the problem?
An ISPConfig server has two Apache webservers running. Apache 1.3.x that serves on port 81, for ISPConfig and Apache 2.2.x which serves your sites on port 80 and/or 443. They also use their own php-version. So that's why you see the difference within the version number.