In my opinion, having tried CentOS 6, latest version of Knoppix & the Mandriva 2011 (which) I did NOT like B|C it is leaning towards becoming a MAC. Mandriva 2010.2 PWP by far came out on top as far as USER friendliness as well as maintaining it's competitiveness in providing a developing environment for QT4, c++, SQL, et cetera.
P.S. I also tried RHE ... did not like.