Well, the best tutorial would be to actually play around with it. If you're using KDE, then its very similar to Windows. The more you use it, the more you will get used to it...
Hang around some linux forums (you can google for them as I dont want to post other forum names here)....read some of the questions and answers, you will learn heaps from doing that.
I say one of the best ways to get familiar with Linux, is to try to find and install Linux equivalents to the Windows programs you use. Installing will be a b!tch at first, but you will soon get used to it.
I just google'd now and found this site :
http://www.linux-tutorial.info/
Check it out , I dont know how good the content is...