well obviously some misinformation up in this thread lol geexbox works WAY better than MPlayer CE,anytime it wouldnt load something id throw the same file in geexbox and itd work no problem.Tried playing some rmvb's in mplayer and it had major av lag. Played the same files in geexbox and they worked no problem. So IMO geexbox is WAY more stable, if you want features that i never use than sure go with mplayer, but if you want stability go with geexbox.
edit: oh and unless they changed it mplayer only sees either the first or active partition on your drive, so if you have many partitions your out of luck lol my movies partition is neither first or active, geexbox shows all your partitions.