I tried to install Kubuntu a few weeks ago on Ubuntu 11.04. Using
"Ubuntu Software Center" - there was so much option to install "which
one Kubuntu package", and obviously it would make a newbie like me
confuse. I think I remember to get the official one - which has support
from Canonical.

The installation moved well, and I got Kubuntu dekstop nicely, well
there is a problem thought - I can't connect to Internet using dial up
modem Pantech PX-500, which my ISP doesn't require user name and
password to connect. In Ubuntu (Gnome), I can connect (via Network
Manager) without them, but not on Kubuntu (KDE). So, I switch back to
Ubuntu.