In the past I used to have a (true) Pioneer drive and an Asus drive based on Pioneer and they both had a nice feature - they controlled the read speed automatically. When I inserted a disk the drive started in a low-speed mode. It was only after a few seconds when the drive detected requirement for fast transfer (for example a copy operation was started) the disc sped to its full speed. If the read speed requirement was low (for example playing an mp3 or a divx movie) the drive remained at its low speed. This way it was almost completely silent for such uses.
Does Asus DRW-24B3ST have a similar feature? Could you try inserting a disc and playing an mp3 - is the drive silent? Of course, I mean without any additional software for slowing down the speed.
Now I have Samsung SH-S203N - while it's a nice drive it's very loud and always spins at full speed when reading a data disc. If I boot up windows with a disc inside my computer becomes a vacuum cleaner for a minute or so. It only slows down when I play a DVD movie or an audio CD.
I'm generally interested to know which drives have automatic speed control so if you know of one, not necessarily Asus, I'd be glad to hear.