I liked the form and function of the WD My Book external drive so I had four 500GB drives around in my home network. I used them to back up my home Windows XP computer that I use as a server and as Time Capsule hard drives for some of my Macs. Unfortunately 2 of the 4 500 GB drives are dead, one after starting to make a clicking sound, the second after it was inadvertantly unplugged while accessing the hard drive. All external hard drives can fail, but I am only batting .500. One unit was 1.5 years old, the other was about 5 months old.I've had better success with my La Cie drives.