BTW- What is CentOS? Is that a Linux variant?
CentOS is a free version of RedHat, it's taken from the RedHat source and then developed from there. Saves the price of RHEL support costs for development platforms, or if you just want a RedHat-alike machine to carry around.
Yep, there are lots of other alternatives out there, but we use this one as it is essentially RHEL.
HTH,
Mark.