The Zune? Tell me your kidding Big D! That thing got the poorest reviews out of any recent mp3 player out there. Bad battery life, size of a brick, crash prone software, won't play playsforsure, doesn't support podcasts. It won't even work with Microsoft's new Vista operating system. No thanks!!!
As for removing the DRM from the m4a files, you can either burn to CD as suggested and then re-rip them, or if you want to do it without needing to burn to a CD do a google for either QTFairUse6 or MyFairTunes6. They'll both do what you want without needing to rip to a CD.