Heres the stroy from Yahoo!
from the article:
The disc has two sets of music tracks: one set of “encrypted” songs that can be handled by CD players but cannot be ripped on computers, and a duplicate set of tracks in the Windows Media format. These can be downloaded from the CD to a computer and then transferred to portable devices or recorded to home CDs.
But these “secure digital” tracks cannot be played on another computer should they be uploaded to the Net.
…
In CD players, the disc plays normally. When put into a Macintosh (news - web sites) or Windows PC, the disc installs software to keep the music secure, and an interactive menu pops up with several links, including one to copy some or all of the Windows Media tracks to your hard drive.
These gahdam CD’s they keep making. It just ends up breaking compatibility and making it harder for us to listen to our over-priced music. This only gives more a reason to download ripped versions of the songs on these CDs. Heck if Im going to install software just to listen to a CD on my computer 
