Using Yum to install Nagios 3 for CentOS 5.4

I was trying to install Nagios 3.x for CentOS 5.4 but only nagios 2.x is surface. You must make sure you install the right repositories for CentOS to get nagios 3.x. To install Nagios 3.x, you will need to install RPMForge first. If you install EPEL only, you might only get nagios 2.x