I recently took over some RHEL 5 systems and I need to get some updates, since I was told my C libraries are way to old. If I get this RHEL 5 system on the net as root, do I need to register my OS (and how) and then get some updates?

Take care,
John

A million thanks in advance.

You need an active RH subscription to get updates directly.

If you login as root at the cmd line and do
replace <something> with eg httpd, it will attempt to contact RHN (Redhat Network).
If it says 'not registered', then you need to find the subscription id the system came with IF(!) it was originally bought and not a free 30 day Trial.
You can also just phone RH support and give them your company name for instance and have them search the registration DB.
If it turns out you don't have a paid subscription, then you need to pay and then (as root)
giving the subscription num supplied by RH.
This gives you a) updates, b) support), c) access to RH Knowledge-base etc
If you don't want to pay, then you can move over to Centos, but that only includes updates; no support/knowledge-base.
You'd have to use google/LQ instead.

HTH