Oops I thought your file was divx. XviD is another variation on the mpeg 4 standard. XviD: http://en.wikipedia.org/wiki/Xvid & DivX: http://en.wikipedia.org/wiki/Divx

Yes both VLC & MPlayer have the divx & Xvid codecs built in as well as others. There's a couple of things one player can do the other can't. I think Sleepless's advice sounds good!