How do i convert a zune file to work with windows movie maker?

i want to add a song i bought from the zune store to windows movie maker but whenever i try to open it, it says this >>>>The file C:\Doents and Settings\Owner\My Doents\My Music\iTunes\iTunes Music\Black Eyed Peas\The E.N.D. (The Energy Never Dies)\01 Boom Boom Pow.m4a is not a supported file type, and it cannot be imported into Windows Movie Maker.