To save time, when installing CentOS, I use the latest minimal disk which installs the latest release with only the bare essentials. It sets up CentOS with a command-line interface, networking and not much else -- really you don't need much to get running.
On a system that I needed Gnome for, I had installed from the minimal disk which meant it wasn't installed by default. To get Gnome running, I did the following:
yum groupinstall &quot;X Window System&quot; &quot;Desktop&quot; &quot;Desktop Platform&quot; &quot;Base&quot;