You can enable Desktop Effects as said.. System -> Desktop Effects.
Make sure you have installed Compiz and Compiz Decorator Qt.
Apartfrom that .. I started using KDE from Kubuntu and believe me I hated KDE thanks to Kubuntu but now I am a Mandriva User
atleast till now
Since you have installed Kubuntu it woun't be wise to remove it .. Follow this guide in setting up Kubuntu *www.howtoforge.com/the-perfect-desktop-kubuntu-8.04-lts-p2
But believe me Kubuntu even full configured is the most pathetic KDE Linux present
Wait few days Mandriva 2009.0 will be release in few days and Ubuntu will hopefully gain my respect again