With the cost of data storage dropping, there’s really no reason not to back up your computer. One effective but underused option is a peripheral known as an external hard drive. High in capacity and convenience, this device allows you to easily copy new content immediately.

Our tests of backup drives found some that, for about $200 to $300, provide enough capacity to accommodate your needs well into the future, whether you have just one computer or a whole network. All that, and they take up no more desk space than a hardcover book and require only moderate technical know-how to install.

The 10 drives we tested varied in ease of use, most due to the design of their included software and the presence of certain features.

Our top-rated single-computer drive, the Iomega Triple Interface Black Series 33090 ($220), provides 250 gigabytes of capacity and has excellent software for both Windows and Mac users, including a native-backup feature that lets you easily find and retrieve files. Yet the term for the Iomega’s warranty and tech support is a paltry three months, and it lacks the one-button operation of the Seagate Pushbutton Backup ST3300601CB (300-GB drive, $260), a very good performer that comes with Mac software and one year of tech support.

Our top-rated network drive, the SimpleTech SimpleShare STI-NAS250 (250-GB drive, $300), combines excellent software for PCs with unlimited tech support.

With all such drives, installation is more difficult with wireless (Wi-Fi) networks than with wired ones, and the time it takes to back up data is about 10 times slower than with wired connections.

None of our tested network drives, and only four of the single-computer units, come with software for Macs. Users of those computers may have to buy stand-alone software, such as Econ Technologies’ ChronoSync v3.3 ($30).

Stand-alone software also is a good idea for people who want to back up data onto CDs or DVDs. Of the six Windows packages we tested, Centered Systems’ Second Copy 7 ($30) offers the most features for the money.