Western Digital has announced an 80GB portable hard drive. Iomega has introduced a 40GB one. Both are aimed at transferring files between computers with the travelling user in mind. Both hold much more than keyfob USB drives yet are still pocketable (6in by 3.5in).

Iomega's Mini hard drive spins more slowly - 4200rpm against WD's 5400rpm. It doesn't need an adapter, getting all its power from the USB 2.0 port. It uses a smaller drive - 1.8 inch versus WD's 2.5 inch. It's also marginally lighter at 99gm as opposed to WD's 120gm. It's not that cheap though, at $179 for 20GB and $279 for 40GB. WD's Passport is cheaper at $249.99 for 80GB and $199.99 for 40GB, but won't be available until the startof new year.

WD says itsPassport product is rugged and reliable - Iomega says the same about its product. Passport comes with a power adapter in case the USB cable doesn't deliver enough power. That means it's a little more complicated to install.

It complements WD's 250GB/7200rpm Media Centre external drive which is not portable. The Media Centre competes with Maxtor's OneTouch product. Both bundle EMC Retrospect backup software and have one button-press backup functions. They are in a different product category compared to these portable drives.

Passport does not have backup software and can be compared with Amacom's IOdisk, offering 20, 40, 60 or 80GB, costing £145 for 40GB. The IOdisk, reviewed here, uses a similar 2.5 inch drive and USB 2.0 connection. It is heavier at 185gm.

Iomega's Mini hard drive can be contrasted with a Siwara pocket drive, reviewed here. This 20GB unit has backup software included and costs £210. UK prices for the Iomega Mini hard drive using a straight £/$ conversion are £112 for 20GB and £174 for 40GB.

The Iomega and WD portable drives both compete with CMS' Automatic Backup System portable hard drive which includes backup software - it costs £148 for 40GB and is also available in 20GB and 60GB flavours. That looks the best value of this portable hard drive collection, but perhaps Western Digital will change that perception come January.