# yum install rrdtool ganglia ganglia-gmetad ganglia-gmond ganglia-web httpd php
However, instead I got the followings
# Error: Missing Dependency: rrdtool = 1.2.27-3.el5 is needed by package rrdtool-perl
To workaround this issue, I've installed in stages. I'm assuming you have installed RpmForge Repository
# yum install rrdtool-perl
# yum install ganglia ganglia-gmetad ganglia-gmond ganglia-web httpd php
ok. It works.