I say the best way to learn Linux is to completely erase Windows from your computer and install Suse Linux (i haven't actually used Gentoo yet, so maybe that's better). Then pick up a book like say The Linux Cookbook by Michael Stutz so learn the basic commands and stuff.
When I first started I installed Corel Linux on a crappy old computer of mine. Not a good choice. I just ended up never using it, because the computer was old, slow, and had a foreign operating system.
Then I did a dualboot with Win2k (new at the time) and Mandrake Linux (don't remember which version, i think it was in the 6.x range). I kept Windows in case I needed Microsoft Office or wanted to play video games. Well, since I wasn't familiar with Linux and the computer still had Windows on it, guess which one I ended up using. I really learned when in December I completely got rid of Windows on my computer and installed Suse Linux. OpenOffice satisfied my needs for an office suite, and I wasn't really playing any good PC video games at the time so I didn't miss that at all. I bought the Linux Cookbook and read the first chapter I believe.. didn't get very far in it because I was so busy with school. I learned some of the more basic commands that I needed. I was no longer afraid of the command line.
Later today I'm going to install Gentoo Linux while waxing my car so I'll see if it's a better choice than Suse.