linux learning

[Charlie Bullen]

Hello, I need to systematically learn linux. I know enough to be dangerous 
now.  What if any certification course gives the best overall linux 
education.  The primary objective is learning. If it leads to a 
certification, so much the better but learning is the key. 

I prefer to work on my own but am not totaly against going to a school. 

I currently administer 2 apache web servers and 1 server for sendmail and 
file sharing with samba. All my learning to date has been of the 3AM need to 
have it working by 8am panic variety, so I know a little of this, a little of 
that but no overall systematic view.

Thanks

Charlie