If you ever need to convert your RHEL 5 server to CentOS 5, you can do the following as root (AT YOUR OWN RISK):
yum clean all
mkdir ~/centos
cd ~/centos/
wget http://mirror.centos.org/centos/5.4/os/i386/RPM-GPG-KEY-CentOS-5
wget http://mirror.centos.org/centos/5.4/os/i386/CentOS/centos-release-5-4.el5.centos.1.i386.rpm
wget http://mirror.centos.org/centos/5.4/os/i386/CentOS/centos-release-notes-5.4-4.i386.rpm
wget http://mirror.centos.org/centos/5.4/os/i386/CentOS/yum-3.2.22-20.el5.centos.noarch.rpm
wget http://mirror.centos.org/centos/5.4/os/i386/CentOS/yum-updatesd-0.9-2.el5.noarch.rpm
rpm –import RPM-GPG-KEY-CentOS-5
rpm -e –nodeps redhat-release
rpm -e yum-rhn-plugin
rpm -Uvh –force *.rpm
yum upgrade
