I originally wanted to buy the 1000GB hard drive. Fortunately, there was a review that drew attention to the "excesses" of the model offered. So I decided to buy the 750GB hard drive from WD. Since I had already replaced the 80GB drive with a 500GB disk a few years ago, I knew how they should be installed. The special screwdriver that Apple uses, I had me back then concerned. So everything happened very quickly. The removed old 500GB drive I built in an external housing with a Firewire connection. Now I needed when reinstalling the operating system (OS X, 10.6.6) the installation wizard only to say: connect with other Mac via FireWire and easily my old settings, programs and files on the new disk was present. And I have again plenty of space on my MacBook2,1 (Intel Core 2 Duo, 2GHz) and the new board runs extremely quietly and reliably. The purchase was well worth it. I am extremely satisfied. Reinhard Stollreiter