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Biometric fingerprint readers give you an easy method to log in to Windows--replacing a typed password with a fingerprint scan--and the software that accompanies many models can protect the privacy of your PC and data. Recently they've also become inexpensive: You can find dependable ones for just $30. Here's how to get the most out of a biometric reader.

Get a good scan: When you "register" your fingerprint with your scanner, its software creates a template to compare against future scans. One way to produce consistent readings is to place the very tip of your finger at the top center of the sensor and then roll your fingertip back onto the sensor plate. If your reader requires you to slide your finger along a sensor, take it slow and steady, from the first knuckle to the tip. Once you have a knack for this, you'll never be rejected again--not by your fingerprint reader, at least.

Use the reader instead of passwords: Most biometric readers come with password management software that lets you manage access to sensitive online accounts, encrypted documents, and anything else you secure with a password. Setup usually involves simply entering your user name and password into either a Windows dialog box or a Web page, and then holding down a vendor-designated hot-key while clicking the Submit button. Thereafter, the password manager will prompt you to scan in your finger rather than type your password. This feature can circumvent keystroke-logging spyware.

Take your passwords with you: If you use one PC at home, another at work, and a laptop while traveling, you probably don't want to enter all your user names and passwords into a password manager on three separate computers. Sony's FIU-810 fingerprint reader, aka the Puppy ($155), solves the problem by storing all fingerprint records and account access settings. Just install Sony's biometric software suite on each of your PCs and register your finger once; any saved passwords will travel along with the Puppy.

Encrypt data: Most biometric software suites also provide some way to encrypt data, using your fingerprint scan as the key. This is the easiest way to prevent someone from reading sensitive files you store on a laptop or portable media. If your biometric software supports this feature, use it! If your laptop ever disappears while you're traveling, you'll be glad you did.

Andrew Brandt is a senior associate editor for PC World. E-mail him at privacywatch@pcworld.com.