Something I'm surprised no one has brought up is
JHymn. Its a free program that strips iTunes files of their DRM without any loss in quality or tag information (as you get when you burn to a CD or record it through your audio card). I did it to our entire purchased music library (about 200 songs out of a total of 6000) so that we could listen to our iTunes music off of our TiVo. It works great.