while VLC may do what you want, it doen't necessarily do it the best. I really like The K-Multimedia Player (epsecially for DVDs) and mplayer/gmplayer/mplayerfrontend.
mplayer is very fast/lightweight player that plays almost anything but its functionality may be limited if you don't know the hotkeys or dislike the command line, where as KMP is a little more resource intensive but it has a rediculous amount of tweaking options