I installed KDE via the sudo apt-get install kde-plasm-desktop command (I wanted less packages than installing the Kubuntu-desktop would give me) and now I get the KDE (or is it Kubuntu?) login screen:

This is what I get, and I can't select the different DEs I have installed. I would like to go back to the default Ubuntu login screen if that is possible. Is there some sort of dpkg command I should run, because that would kinda make sense.

Thanks in advance (that is, if you solve my problem. If you don't well, then I suppose I could thank you for trying to help...I dunno :D)