All this talk about quiet.. loud.. and whatever inbetween.. really doesn't mean much to anyone. It's all relative. I personally have a small amount of hearing loss.. so I don't hear 100% of what everyone else does. However, I do hear certain ranges incredibly well.
Before we can go around saying one drive is loud.. etc.. we need a noise standard. Preferably one where decibels are measured in a quantitative and scientific way that we can establish as a standard. We then add to that measurements for idle, dvd game play, dvd movie play, cd play etc.
Short of that.. all I see here are people using their subjective sense to guage noise and compare it.
In my unscientific testing.. (I don't have a proper db tester) I have made recording using my mic turned all the way up and extended to where I keep one of each Xbox and Xbox360.
Overall, I found my 360 to be quieter, however, on Game DIsk load, it peaks a bit higher. (keep in mind.. that the recording does not exlude the noise of the fans as they ramp up speed.
Anyways.. loud.. quiet.. we need a standard. Otherwise.. it's just a bunch of hooey.