which is more user friendly ubantu or knoppix?

Well, it's tough to compare. Ubuntu is a complete full-featured traditional distro, and Knoppix is a liveCD. LiveCD's are nice because you never have to install. Traditional distros like ubuntu are nice because if you want to add a program, you just apt-get it instead of CD-remastering.

Both are remarkably user friendly and full featured, but they target different audiences.

I don't really know 'vanilla' Knoppix but I have been in contact with some Knoppix-based LiveCDs. The two I tried (Kanotix and Kurumin) had a script to install it to HD. Once installed, adding programs is as easy as Ubuntu - and, after installed, usability (and user-friendliness) in Kubuntu (because I prefer KDE) and the Knoppix-based LiveCDs is about the same level - both are great and fun to use.

If you plan on installing it to the harddrive, I recommend Ubuntu. Ubuntu has one thing many distros lack for newbies: automatic updates.

You can install from the Ubuntu LiveCD so you have both. As to ease of use, I find live CDs annoyingly slow for my tastes. Ease of use comes from a number of places. One is the choice of GUI as Gnome, FDE, Fluxbox and etc. IMHO, KDE is good but Gnome is more intuitive. Others do an adequate job but tend to be more focused on small size than features. Another big area is package management. Without arguing the the old RPM vs DEB thing, Ubuntu seems to have done a very good job in building packages to simplify the installation process. To install XMLTV on Ubuntu its only one package, on SuSE I couldn't count all the bits and pieces and it took hours to install. Also important is the community. Ubuntu makes excellent use of web support and has a structure which is well used by its many users. Linuxquestions.org is a great place but for Ubuntu, Ubuntu's forums have even more participants. I check, learn from and help others in both everyday. To me, Ubuntu is the winner in all three key categories.

Yes, I should add that as a Ubuntu user I can assure you the community is very active and friendly. And another rarity in desktop linux - you can buy professional tech support for Ubuntu (If you get really desperate/time crunched).