You want to migrate from the iPod to the Zune but the main reason you haven't made that jump is because you have your iTunes library. I'm sure that's a very common reason for not coming over to the Zune world. (Ok, maybe not, but I'll maintain my delusion.) This is a serious issue though and if you do want to change platforms, then your only options are mostly time consuming and wasteful.

An M4P converter allows the owner of protected audio files such as those purchased from Apples' iTunes to either remove the DRM protection from the file or convert the file into a variety of other audio formats such as MP3 or WAV. These formats can then be used for creating audio CDs or opened for listening by other media players or devices.