I have a system running RHEL5 that is not connected to the internet. I need to provide security updates to operating system. Downloading each rpm is not feasible since some updates may create other dependency issues. Looking for alternatives.

I have been advised to set up a mirror system to obtain updates, then copy them to the non-connected system. Is this the best alternative? If so, how do I hold the files on the mirror system so they can be put onto removable media for installation on the non-connected system prior to installation on the mirror system?

Thanks.

Contact Red Hat that is one of the reasons you are paying for the support .The updates is the other.
https://www.redhat.com/support/

and they can walk you through it .
It should be close to the CentOS wiki how to
http://wiki.centos.org/HowTos/CreateLocalMirror