The My Book Premium ES Edition is much like Western Digital's past My Book drives -- this one defined by offering USB2.0 and eSATA.

Design/Features
The usual My Book shape is here, along with the "Morse code" perforated air holes, and the blue circle activity light at the front. If you install Western Digital's Button Manager, the LED can also show how much capacity you've used of the hard drive -- it's not frightfully accurate though, only lighting up segments that roughly equate to 17 percent of capacity. The feature won't work with eSATA mode either -- although ultimately you're much better off simply using the drive properties in your OS to get a more accurate reading.

The box itself is fanless, the hard drive never getting hugely loud. Oddly, despite the eSATA connection no eSATA cable is included, leaving you to purchase your own. A USB2.0 cable and power brick make up the rest of the package.

EMC Restrospect Express is the included backup software, with both Mac and PC version available, servicing the oft overlooked Apple crowd.

Western Digital includes a one year warranty, which is to us scary for any hard drive product -- especially in the face of the five year warranty offered by its Studio Edition drives, Maxtor's One Touch 4/Plus or Seagate's FreeAgent Desktop/Pro.

Performance
The Premium ES Edition performed as expected over USB2.0 and well over eSATA -- but we wonder if Western Digital isn't shooting itself in the foot here. Despite a lower RRP, you'd be better off picking up the equivalently sized Studio Edition for a little bit more, getting the eSATA cable, firewire capability and an extra four years on your warranty.

The My Book Premium ES Edition is available in 320GB and 500GB capacities.