The Linux Documentation Project
is a good site to find information. I bookmarked that one in my early days of Linux, and still find myself referring to it every once in a while.
Rute's Linux Tutorial
is very extensive.
Also, this is just my opinion, but the best way to learn Linux is to use it on a daily basis, for everyday tasks. I forced myself by wiping windows from my hard drive and then installing RedHat (7.3). It was easy to get the system set up, and I was back on-line within minutes. When I encountered problems, I had no choice but to read and learn. The hardest part is thinking outside of what you're used to (the window's way of doing things). Now I find myself almost lost on a Windows system because I think more in terms of Linux. On my home computer, I still am using Linux exclusively, and like it more than I ever did using Windows (I definitely don't miss those stupid blue screens
Finally, This site is probably the most valuable resource I have found to help with almost any problem. If you run into something, chances are somebody else has too, and there will be a discussion of it here. Never underestimate the search features of LQ
Good luck and Welcome