Although the Western Digital 'My Book' Studio Edition II is nominally aimed at Mac lovers, there's little to keep PC users from enjoying this flexible and energy-efficient 2TB unit.

With three types of connections spread over four ports on the back of the device (2 x FireWire S800, 1 x eSATA and 1 x mini-USB 2.0), the My Book is equipped for the modern computer user — although those with FireWire S400 connections will need a converter.

Inside the elegantly simple plastic exterior, which is virtually identical to the previous Western Digital My Book Studio, are two 'Green Power' hard drives that provide the storage. Due to the drives being formatted for use with Macs, PC users will need to convert the hard drives from HFS+ to NTFS via Disk Management in Windows Vista. This will leave two drives of 905GB each to play with, for a total of 1.81TB of storage.

By using the WD RAID Manager program that comes bundled with the storage centre, the drives' RAID configuration can be changed so that they mirror each other. This means that if one of the drives is disabled or damaged, the data will still be safe and available on the other.

Another useful piece of bundled software is WD Anywhere Backup. This simple program allows users to quickly select the folders they want backed up as well as the proposed drive location in three easy steps (the software code required to extend use beyond 30 days is hidden away on the back of the fold-out manual).

Both drives are proudly green: our power readings showed that both when reading and writing the WD hit a peak energy consumption level of 17 Watts. When the connection to a computer is severed, the 'My Book' detects this and drops power consumption to a low 7 Watts.

The My Book's performance is nothing spectacular. During testing we transferred 5GB of data between it and a 320GB Seagate hard drive that spins at 7200rpm. For the S800 FireWire connection, the My Book managed write and read speeds of 26.57MBps and 39.73MBps respectively, while the USB 2.0 managed to score 28.97MBps and 31.10MBps. The eSATA port connection was more impressive, managing to read data at a speed of 49.38MBps and write at 58.95MBps.

At a price of $699, this device offers 2TB of energy-efficient storage for 39c/GB. If you're a user who needs plenty of space constantly at the ready, then the My Book may be for you. If you're looking for performance, however, look elsewhere.