WD  250 GB USB 2.0/Firewire External Hard Drive with Dual Option Backup and USB ( WDXB2500JBRNN ) Instant addition of massive data storage capacity for PC or Macintosh Dual-option backup--automatic or on-the-spot One conveniently located on the front for easy connection of USB peripherals such as a keychain drive, printer, keyboard, or mouse 7200 RPM rotational speed and 8 MB cache for maximum storage performance Includes Dantz Retrospect Express backup software