XViD encoded movies can be played using DivX.5.1.1., which (if you havn't already installed it) can be downloaded
here.
(Note: you need not install the player which is included in this "bundle"; you can simply deselect it).
In DivX5.1.1 codec, please check settings on Tab "Quality". These can be reached directly through [Start] "Programs"/"DivX"/"DivX codec"/"Decoder configuration Utility". If "Support Generic Mpeg-4" is checked (selected) it will also play XViD encoded movies.
You can also decide to play XViD encoded movies using XViD's codec, which you can download i.a.
here.
To use that, you will have to leave the box "Support Generic Mpeg-4" of DivX-codec unchecked.
BSPlayer will then use XViD-codec for XViD-encoded movies and BSPlayer shows this under "Options"/"Filters", where you can also set codec's properties.
Edited 17 July 2004: Link to DivX (5.2!) download address changed