If you're looking for fast external storage, to supplement existing internal drives, to provide quick and reliable backup or to transfer large amounts of data from one PC to another, you should look at a plug-in, external hard drive. There are two main ways of connecting these, by USB 2 or FireWire (the original USB 1.1 standard is too slow for a hard drive and will be a bottleneck in transferring data). The Momobay CX-2 can use either standard.

This is a neat little device, based on a 3.5-inch notebook hard drive, and can be bought as a complete unit or as an empty case, leaving you to fit a drive of your choice. If you're on a tight budget, you may be able to save some money by buying a drive from eBay and fitting it in a Momobay case, but the price for a complete 30GB unit is pretty reasonable.

At the back of the drive are three sockets, one for USB 2 and the other two, at both standard sizes, for FireWire. A cunningly contrived three-way slide switch selects USB 2, FireWire or FireWire data and USB 2 power. Most 3.5-inch drives take so little current you can run them directly from a FireWire socket, without a separate power connection, but in case you do have problems (we had none during testing), you can use a higher-current USB 2 port instead.

We copied a 100MB collection of files with a range of different sizes to and from the Momobay and completed each of the runs in between 11 and 12 seconds. We saw no noticeable difference in transfer speed between USB 2 and FireWire connections and overall the performance of the drive is good.

Dividing the cost of the drive by its capacity returns a cost per MB of 0.58p, which is low. Although it's beaten on this measure by devices such as a CD-RW, it's considerably faster and could even be used to read and write digital video data, while editing.

The Momobay comes complete with a leatherette pouch, providing some physical protection, and can be supplied formatted to your needs, if this is requested at the time of purchase.

This is a neat and cost-effective solution to all kinds of external storage problems. It's an ideal device to carry your important data in an inconspicuous way or to add extra capacity to a PC with a crowded hard drive.