I have used both Ubuntu and PCLinuxOS. The biggest difference is in one is KDE based, the other is gnome.
While both will get one started in Linux, neither comes with the development tools necessary to compile software. That's why I like Slackware. But it requires a lot of configuration, and extra stuff to do to get multimedia stuff going. Its not hard, but a bit daunting to the new user.
Everything you need is available for both Ubuntu and PClinuxOS, you just have to spend a lot of time in the repositories.