There are many MPEG multimedia players about; but, if you`re talking about totally free ones, there aren`t so many about. And on top of that if they are as complete as MPEG Player, then even better.
To start with, MPEG Player automatically associates the MPEG extension with the player; so, with a simple double click you can open and then play it. It has the basic functions of any other player: play, pause, go to a specific track, show it on full screen, etc.
With MPEG Player you can also create your own playlists (and save them to edit in the future). It also has an internal searcher to make it easier to locate any song in a list.