I thought I might try to update some KDE base and graphics system packages from the installation cd and let YaST reconfigure everything.
Things got worse.
Even though it seems to load runlevel 5 services, it ends up in a console login prompt like in runlevel 3. I login as root, but I can't make it do `init 5`. It responds nothing. As if I'm running runlevel 5 already, just without any graphical environment.
Now, I consider myself lucky to have looked up in that last kde session how to tell grub where the windows are installed, because I'm running them at he moment.
I'm seriously considering reinstalling everything. It's the only thing I know how to do. My understanding of linux is still pretty windows-y.