I can understand your state of mind.Nice to see your urge to learn and zest for Linux.
First of all I would suggest you to Not to go for RHEL5 if you dont have Licensed version,instead go for Centos-5.
You can try even Scientific Linux (SL).
The base SL distribution is basically Enterprise Linux, recompiled from source.
Follow this link and configure each and every thing mentioned in this link:
This link covers most of the practical aspects most of the system admins do in there day to day task.
Few other good links are:
You can also refer LQ's http://wiki.linuxquestions.org/wiki/Main_Page
Also refer some books like Linux Bible,Linux Complete.
You can also go for some certification like RHCE,Ubuntu Professional Certification,LPI,Novel Certification for Linux.
At times going for certification helps as for most of the companies certification is must.
So follow this and you will succeed.