Dvdnav plugin can be found at
http://dvd.sf.net/. It may slow Xine down a bit.
Played a dvd recently (region 2/4) and thought there was a problem as it wouldn't load. Ran Xine in xterm and realised it was getting css keys. Was patient for about 20 minutes and everything worked fine.
Recently tried Ogle. Installed from source and that worked fine straight away.