improve video quality in mplayer
 

how can i improve video quality in mplayer ?
(the same movies had better quality in windows xp but with different players)
(i have fedora core 3)

Sounds odd to me. Either get another codec/try other backend-player, or play the movie in a correct-sized window (scaling > 100% will make it look bad), or fullscreen if it's supposed to play like so.

Have you tried Xine-backend, or gstreamer? Did you get the same result? I doubt if this has anything to do with direct rendering, but can you test?