With both the popular USB 2.0 and the ultra-fast eSATA 3 Gb/s interfaces on board, the 500GB My Book Premium ES Edition external hard drive offers universal connectivity and unbeatable performance in one high-value package. Installation is a snap because you don't really "install" this drive, you just plug it in and it's ready to use. There is no CD to install, the included software loads from the drive the first time you plug it in. The drive's two interfaces offer great flexibility. For convenience and compatibility among multiple computers, USB 2.0 is the way to go. The ultra-fast eSATA interface gives you speed comparable to a state-of-the-art internal hard drive. This is the future of external storage made available today. The capacity gauge allows you to see at a glance how much space is available on your storage system. (Works with the USB connection only)This drive works with both Windows and Macintosh computers. It includes EMC Retrospect Express backup software.