I have openSUSE 11.1 (KDE4) installed above old openSUSE 10.2 installation, so that my old accounts survived and working.
The only one problem I have with Display resolution. In root account it is 1920x1200 (as my monitor supports) but when I login into user account I get only 1280x1024. I can then manually change it to 1920x1200, but on next login it again appears 1280x1024. Apparently this resolution sits in one of my old configuration files.
Configuration files for your display are in /etc/X11/xorg.conf. Usually you can use sax2 to configure things.
Found in kickoff > system > configuration > Configure X11 System.
Take a look in Systemsettings-Display. Your resolution should be available there. Change it, apply, Save configuration and you should be done. On the fly.
If you intend to do changes in the xorg.conf file, you might want to make a backup copy of your current file which works.
sudo cp /etc/X11/xorg.conf /etc/X11/xorg-old.conf