While desktop drives have the most capacity, they are larger than portable drives (about the size of a book) and require an external power supply (you need to plug them into a wall or power strip). Portable external hard drives, on the other hand, come in smaller capacities than desktop models but are powered through your computer's USB port. This makes them a good choice for laptop users or anyone who needs more portable storage.
Since the advent of USB 3.0, manufacturers have been busy updating their external hard drives with this new, faster interface. Examples include the Western Digital My Passport Essential SE (*Est. $100 for 1 TB), which has quickly become a favorite of several top reviewers, including Macworld, PCMag.com and PC World.
The Western Digital My Passport Essential SE outscores most portable as well as desktop external hard drives on the strengths of its simple-to-use backup software, single-cord connection (no AC adapter required) and quiet operation. Its small size is praised by other reviewers, though some note that the glossy plastic case shows fingerprints and can feel flimsy.
Drive speed can be an issue, however. That's not apparent if your system still uses USB 2.0 ports -- which is the case with lots of computers and laptops, including all Apple products at present. In fact, the Western Digital My Passport Essential SE is among the fastest USB 2.0 external hard drives available for Windows and Mac OS users. For those with newer systems that include USB 3.0 ports, however, things aren't as rosy and some reviewers grouse about the drive's speed compared against other USB 3.0 options. Still, reviewers agree that the Western Digital My Passport Essential SE is a great value that offers the ability to take advantage of at least some of the speed benefits of USB 3.0 the moment you get a computer that's equipped with that port. The Western Digital My Passport Essential SE is also available in a 750 GB configuration (*Est. $85), and in four colors. The Western Digital My Passport Essential is similar, but is only offered in a 500 GB version (*Est. $75).
For a less expensive option, consider the Seagate FreeAgent GoFlex Ultra-Portable ($50 for 320 GB). The FreeAgent GoFlex Ultra-Portable is natively a USB 2.0 drive, but it can be upgraded to USB 3.0 at any time by purchasing a $20 adapter.
How does the FreeAgent GoFlex Ultra-Portable Drive perform? Very respectably -- especially for a portable hard drive -- according to tests conducted by Macworld, CNET and BigBruin.com. It zips through tests using USB 2.0 and FireWire. Using USB 3.0, CNET found plenty of external drives that are faster -- but they're desktop drives, not portables. Seagate does offer a desktop version, the Seagate FreeAgent GoFlex Desk (*Est. $70 for 1TB), but several reviews are leery because it runs hot. The GoFlex Ultra-Portable Drive comes pre-loaded with backup software, and you can use it interchangeably with Windows and Mac computers, making it "great for multiple platform families," BigBruin.com says. If you like the FreeAgent GoFlex Ultra-Portable Drive, and can budget for it, it's also available in 500 GB (*Est. $65), 750 GB (*Est. $90) and 1 TB (*Est. $90) configurations.
If you're looking for the easiest possible backup method, experts and owners agree that the palm-sized Clickfree C2 (*Est. $95 for 1 TB) portable USB 2.0 drive is the simplest you can buy. It backs up your key files every time you plug it in -- you don't have to do a thing. Even if you use it to back up multiple computers, the Clickfree C2 will automatically detect each different computer and store the backups separately. It works fine with both PCs and Macs in The Wall Street Journal's test, although another expert source says you can't alternate between the two without reformatting the drive and erasing the data.