I have an mpg file that I want to play but its not supported by Windows Media Player, Quicktime or DivX, so how do I find out what codecs I need to play this file?

There's a program called G-Spot that tells you which codec a video file needs. But if you want to get rid of the problem with codecs, I would suggest the VLC player to you. It is free, compatible with almost all video formats and you can find it here: http://www.videolan.org/

You could also check the k-Lite Mega Codecs in the Utilities Section of the Tech Files over @ the Lair. The K-Lite set offers just about every codec and player you'll ever need.

Thanks very much, I'll try them out