if you want to stop media center from auto adding the music you need to tell media center to stop looking in the folders.
to do this, open media center and go to settings.
from settings, choose "media libraries". select "music" and hit next.
on the next screen, select "remove folders from library" and then hit next.
uncheck any folders that show up, and then hit next
select "yes, use these location" and then finish
when its done, you should no longer have the music showing up in media center
hope this helps,
Another guy named Steve