I have SuSE 9.1, and it took me a very long time to get MPlayer running correctly. I can't even remember how I did it. I did, however, get the mplayer plugin working with little effort. You can get it here:
http://packman.links2linux.org/?action=319
The plugin allows you to watch Windows Media, Quicktime, and any other formats as long as you have the codecs.
For DVDs and any downloaded files (such as divx), I use Xine exclusively.
Regarding RealPlayer, you should definitely remove previous versions before you install RealPlayer 10. To get the plugin to work with your web browser, go to the directory where you installed it, something like /usr/local/RealPlayer/mozilla, and you'll see the RealPlayer plugins. Copy the plugins to your mozilla/plugins directory (or whatever browser you use).
If, for some reason, YaST cannot resolve your dependencies, I've always found it useful to search at
http://rpm.pbone.net It allows you to type in the needed file (i.e. libsuchandsuch.so.1) and it will show you a list of rpms that have that file the distributions to which they belong. Also, with "advanced search" you can limit the search to only SuSE rpms. Very useful, IMO.
I still have my directory of all the rpms that I've needed to get everything running on SuSE. If you want, I can provide a list for you.
Good luck and try to have fun...that's all part of learning (can you tell I'm a teacher?).
Kazim