Nope it's not a soundtrack or anything..I just heard somewhere it could be for the monkey, but somehow I find it hard to believe they would package a whole new disc just for a pet monkey. Apparently a lot of people that preordered didn't get their monkeys. But it just looks like another install disc, it says "DISC III" on it the same way the other two do..it prompted me to insert it right at the very end of the install process and only loaded something from it for about half a second before it finished.