I find the MediaPlayer 6.4.6.8 to work quite well, try googleing for it

If it is DivX or X-vid you will find the right codec here

http://www.divx-digest.com/software/index.html

On that same page you can download a free program called VTafreecodec which after you have installed and opened it, you can drag your videofile to and get all the info you need to find the right codec