You can just use your standard player that
comes with Windows or with the Mac but if
you wish to edit the file you will need
to get a better program. To play the files
using the standard players just double click
them in your file management utility (i.e.
Windows Explorer).
Microsoft's Media Player is designed to
solve all of your multimedia file needs
by supporting a great number of formats
of audio and video.
To get this program you'll have to visit
Microsoft's site.
