Sorry, I can't help with Knoppix. As long as you are trying out distros, I am also a newbie, and tried a bunch which were all nice. The reason I settled on Ubuntu (aside from its popularity) was the quality of support for new users. Check out http://ubuntuguide.org/wiki/Ubuntu_Edgy
and see if this "how to" type of help appeals to you.
If you google, I found a place on the web that has in interactive program that will help you find the right distro for you. It makes a recommendation based upon your wants, needs, experience, etc.