there are a few games that make very little noise when playing: Fallout 3, Halo 3 and Infinite Undiscovery are just some of those games.
Someone mentioned to me these games the disc spins much slower but I've no idea thats true.. All I can definitely say is that the fans don't go into rocket drive when they are spining.. and I can barely hear the disks "twitching"
Anyway installing the games to the HDD really does make a difference to the noise..