CentOS is the Open Source and free distribution which bundles the EL packages from RedHat, which is the RHEL.
When we got a new server for our team i suggested that we run both our development and production server over it using virtualization and also suggested using Xen Para virtualization for it and finally to use CentOS 5, and since all were my suggestions I was handed the task of setting up the server.
I tried to download CentOS 5 DVD but due to various reasons it failed. Since I had Cent OS 4.4, I thought will install CentOS 4.4 and upgrade, but it is way too complicated
So finally I downloaded CentOS 5 CD #1 and decided to do a net based installation.
Came to know that Over the internet install doesn’t work
So, I I had to do just a base install, and install the rest as required, and did as instructed here. I call this CentOS From Scratch!