Can I change the media player that opens with the Media on on my keyboard?

I recently downloaded the Zune software so I could transfer files to my Xbox 360. I don't like the Zune layout so I want to us Windows Media Player, I haven't got Zune set as the default program for any files. How can I set it so when I press the Media on on the Logitech keyboard it opens WMP like it always used to!