My back 640's made no sound at all, did not even vibrate, then I got my 2TB one and boy on spinup(think it is a 4 platter job or something) does it make it self known. It also seeks rather loud(not old 40gig loud tho), but this is in a rather quiet system.
I am half tempted to pop a red into my media center(I currently have a 1tb wdc blue notebook drive in that system for storage) to see how quiet it is. I do not need speed(It has a small 128 gigabyte M4 for windows and programs), just space.
Back on topic. sorry op.