We now consider the per-gigabyte cost of several various backup solutions using an optimistic 2:1 total compression ratio when necessary.) We selected Iomega's own hard drives to represent that segment of the PC back-up market -- nothing like a little intramural competition, eh?

All product pricing is based on average Web prices as of press time. One Rev disk is thus priced at $65, and the drive retails on average for $530 -- although it ships with a disk. Accordingly, backing up 250GB onto Rev, for instance, will require two Rev 70GB disks, at 2:1 compression. Since one disk is included with the Rev USB 2.0 drive, that requires the purchase of only one additional disk.

(The $669 HP StorageWorks DAT 72 kit, scheduled to ship later this month, also comes with four DAT 72 tapes.) One included DVD is budgeted into the cost of our sample DVD burner, the LG GSA-5163D External, and our DVD pricing takes multi-packs and spindle bundles into account (for instance, a three-pack of DL DVDs typically runs half the cost of a 15-pack.)

We're leaving out Blu-Ray and HD-DVD for the time being -- even though Blu-Ray disks can hold up to 50GB, the initial costs of this new technology are high, and likely to drop dramatically over the next 12 months.

The Rev shines in several scenarios here. Against its archrival DAT 72, it performs admirably, with savings over tape decreasing as backup requirements increase.

Using DVD media and hard drives as backups tends to do better on a cost-per-gigabyte ratio. However, it's important to note that these media are not especially long-lasting, are prone to more types of failure than are tape or Rev, and have additional drawbacks. DVDs, of course, are prone to scratching, and their longevity is neither proven nor especially promising. It's also not especially pleasant to think of the effort involved in the task of backing up 250GB to DVD, each of which can contain only 17GB maximum after 2:1 compression. Hard drives are typically less-than-portable, offer questionable long-term reliability while in regular use, and suffer from the annoying habit of succumbing to silent death when not in use.