If you want to stay near RH, use fedora core to familiarize yourself with RH architecture. It's good for end users and includes many HOW TOs and GUIs. CentOS is good to get a feeling for older and more stable feeling that RH provides. If you look around you might find someone that will give you a copy of RH, after all RH is selling a service. You can also sign up for a 60 eval at https://www.redhat.com/apps/download/
. They used to offer their cd set for sale w/o 1 yr subscription and yadda yaddda yadda. If you want to be a linux admin..spend the 80 dollars and go through every tutorial over every server. Within that 1 yr you should be trained, :P . Or go to college! My professor gave me my first nix cds and they were RH.