You might find this of interest - it is primarily related to iPODs, but is still of interest...
First, a little background. An iPod is an MP3 player, which means (duh!) that music must be in MP3 format (or AAC, AIFF or WAV) to work. Okay --- not really a problem, except that alot of what is happening in (legal) digital music is happening in Windows Media Audio (WMA). Why WMA and not MP3? Because WMA includes security measures that allow the publisher to restrict what you do with the music. For example, one publisher may allow you to store the song file on three computers, a digital music player and to burn three CDs. Another publisher may allow ten computer copies and ten CD copies. So WMA offers record labels more control over their digital properties than MP3 does.