I vowed to switch to KDE after trying for a few months to find an alternative to Gnome 2, which is going the way of the Dodo. I ran into two problems initially. The system sounds were distorting and I hated the annoying blue shadow on active windows.
The fix for the first problem came when I installed the phonon gstreamer backend, though I’m not sure this was exactly the fix as I never switched to that backend in the settings.
To fix the annoying blue shadow, go to System Settings -> Workspace appearance -> Window Decorations. Click on the Oxygen theme and then click “Configure Decoration”. Click the Shadows tab and change the colors under “Active Window Glow”. I made my inner color a dark grey and the outer color black. I like this a lot better than the bright blue.