The media player recommended as the best available, by nearly all of the 'regulars' here in the Technology section, is VLC.
The media player recommended on Radio 4's technology program is VLC.
The media player recommended by the technology programme on BBC World Service is VLC.
The media player recommended on the BBC News 24 technology programme is VLC.
The media player by several PC magazines is VLC.
The media player almost universally condemned by just about everyone is Windows Media Player. (Like most Microsoft products, it seems to start off poor and then gets worse with every so-called 'upgrade').
Er, does that answer your question?
http://www.videolan.org/
Chris