I recently migrated to Ubuntu Gutsy and am trying to manage my music files.  I was able to open m4p files that were associated with iTunes in Windows, however, I am unable to open those that were purchased and downloaded through iTunes.  I attempted without success to open these files in other programs, and received a message in Movie Player that these files were encrypted.  Anyone know of a way to make these files playable in Amarok?

This is a problem that I too had. It involves circumventing DRM and is thus technically illegal. Hunt around on google though there are several tools that will either strip out the DRM or just plain convert your music to .mp3.