While my 36LZX (18.3 Gb) is not the quitest drive in the world, it definetely not as loud as Seagate Cheetah X15 (I have both of these drives at work, and I can compare them to each other). As far as speed differnces in the everyday business, I can't really say there is too much between them. Both IBM and Seagate let open pretty much any application virtually without waiting hourglass. I hope this helps,