You should keep a backup of all the records you store on your PC, but leaving the files on a run-of-the-mill unencrypted hard drive can expose personal information like credit card and social security numbers to thieves that may walk off with the drive. Maxtor's BlackArmor ($120 list, for 160GB) external hard drive makes that data as secure as it can be without employing "Top Secret" encryption levels.

The BlackArmor is a little sleeker than the average external portable hard drive, with two LEDs on the side and a friendly Seagate Secure logo on the top panel. Faux brushed-metal accents make the drive stand out when placed next to drives like the SimpleTech Signature Mini Black Cherry. Yet it's what's inside that matters. Maxtor's BlackArmor line consists of secure hard drives with 128-bit AES encryption. The drives are encrypted from the factory, so you are protected right away. You will, however, have to set up the drive for use on Windows PCs. (Macs and Linux PCs don't support the BlackArmor software.)

When you plug in the drive, a pseudo-CD drive—a partition that mounts and acts like an auto-loading CD) —comes up and asks you to first enter the key code on the bottom of the drive, and then choose a password to unlock the drive, along with a hint in case you forget the password. That password can be a simple one with six characters, but for maximum security you can choose a 32-character mix of numbers and letters. A handy indicator in the setup screen tells you if your password is weak (for example, "ABCDEF"), or if it is very strong ("N1tt4agm2c2ta0tC4sa7yaotcannc"), which is handy for helping you to pick passwords that aren't easy to guess or "brute force" open. Once the password is entered, the Unlock screen comes up. After you enter the password again, the drive mounts for real, and then it acts like any other hard drive. You can copy files to it via drag-and-drop or with the included Maxtor backup program. That program is a simple one, designed to back up selected files from folders of your choice, like the My Documents folder.

Since the data is encrypted as it is written to the drive, the security works immediately and continuously. If anyone were to come by and grab the BlackArmor drive from your PC, they would need to enter the password to access the secure drive. Likewise, if you lose your password, you won't be able to access your files, either. Your data will be protected even if the drive is physically removed from its shell and put in another notebook PC.

The BlackArmor's 128-bit AES encryption isn't the highest level of security available to the consumer market (that would be 256-bit), but it's good enough for the U.S. government to allow it for all except "Top Secret"–level documents, so it should be good enough for you. It would take a bunch of networked computers years if not decades to crack a 128-bit AES key. People such as accountants or store owners who deal with personal data should think about using encrypted hard drives to back up or store their data.

The drive is an adequate performer. On our PCMark05 HDD test it achieved a score of 2,769, which is average for a USB 2.0 drive. The Editors' Choice Lenovo ThinkPad USB Portable Secure Hard Drive is a bit faster at 3,126, a 13 percent difference. Copying via drag-and-drop was quick: It took 53 seconds to copy our 1.2GB test folder. (Under a minute is a very good score.) It's not the fastest portable drive on the market, but its speed is decent.

My small list of nits includes the almost-mandatory installation of the Maxtor Manager software. You can create the original password when you first set the drive up, on any Windows PC, but if you ever need to change it, you'll have to do so on a PC with the Manager software installed on it. The flip side to this is that after a password is set, you don't need to install the software on every PC you connect the BlackArmor to. The Password Unlock utility works off the drive's auto-loading pseudo-CD partition. Once unlocked, the drive works like a typical drive for reads, writes, and copies. Another nit is that the drive doesn't work with Macs or Linux PCs—the auto-loading program is Windows only. Last but not least, the included backup software is geared toward auto-saving your files, not your whole PC—OS, apps, and all. Look to drives like the Maxtor OneTouch 4 Mini for that capability.

The Maxtor BlackArmor is a smidge more expensive than more standard (unencrypted) hard drives like its sibling, the Maxtor OneTouch 4 mini ($99 list for 160GB), but you are getting extra protection from prying eyes with the BlackArmor. The 320GB version of the BlackArmor lists at $169.99, $49 less than the Lenovo Secure Drive of the same capacity. However, the Lenovo drive is much more versatile, easier to use, usable on other platforms like Macs, and it's faster as well. Ultimately, the Lenovo edges out the BlackArmor, but only just. The BlackArmor is well worth consideration, particularly if you use—or require your users to use—strong passwords to protect your data.

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