If you're running Linux and want to watch your legally owned DVDs on your legally owned PC you might find that some distro' do not include the code to view them. Opensuse 10 is a case in point.
Apparently WinXP is the same - Media Player cannot run a DVD unless you have the codecs installed from elsewhere - such as WinDVD.
The following URL should help improve your viewing pleasure.
Make sure you remove the existing "xine" and "kaffine" from your suse10 system first as they have been scuppered.