Lock Down Your Mac
Most Mac users know someone who's had a notebook stolen - or they've been victimized themselves. MacBooks and MacBook Pros are especially attractive because of their high resale value. So MacBook owners have to be extra vigilant about securing their notebooks.

First - and, yes, it's a shame we even have to mention this - you should never take your eyes off of your laptop. Improve your odds by sitting away from main entrances and exits. If you use your notebook in public places often, consider a physical security device like a cable or an alarm. Kensington's MicroSaver line includes notebook locks ($29.99 to $69.99) that are subtle enough so you won't look out of place when you wrap them around a table leg. The keyed and combination locks work with the built-in Kensington security slot on your MacBook or MacBook Pro. (Kensington makes locks for desktop machines too.)

If the unthinkable should happen, you'll appreciate having protected your 'Book with Orbicule's Undercover ($39). This theft-recovery system goes to great lengths to help you get your 'Book back. Not only will Orbicule help you track a stolen notebook, Undercover can snap pictures of the thief in action using your 'Book's built-in iSight camera. If your Mac notebook came with an Apple Remote, you might also try Orbicule's beta software TheftSensor (free). It works with the 'Book's motion sensor so that once you press Play on the remote, any time the notebook is moved, an alarm will sound. It's not exactly subtle, but it's a deterrent.

Keep thieves from helping themselves to the five-finger discount on a new MacBook (yours) with a Kensington MicroSaver lock.

Create Your Own Secure File Vault
Let's say you want to password-protect a folder or a bunch of disparate files on your Mac. Maybe it's because you want to save this collection of files on a shared resource like a file server or an external drive, but you don't want anyone, even your system administrator, to open it. The solution: Create an encrypted disk image to protect your valuable information.

A disk image has a .dmg file extension. When you double-click a disk image, it appears on your desktop as if it was an external drive. A mounted disk image behaves like an external drive. You can copy files to and from it. And when you're done, you just drag it to the trash and it unmounts like an external drive, yet leaves the DMG file intact. To create an encrypted disk image, we'll make a new image, give it a password, and save it. Here's how.

Step 1: Open Disk Utility (/Applications/Utilities). Select File > New > Blank Disk Image or just click the new-image icon. Enter a name for your disk image. Since you'll be using this to save sensitive information, we recommend not calling it "My Credit Card Numbers" or "All My Passwords."

In Disk Utility, a new file is a new volume.

Step 2: Choose a location for your disk image. You can save it anywhere on your Mac, or on an external hard drive or network volume. Pick a size that's going to be big enough to hold your files. The easiest route is to choose a preset for recordable media such as CD-R or DVD-R. This way you know it will fit if you want to burn a backup.

Choose a size for your vault that's big enough to hold the files you want to hide from prying eyes.

Step 3: Under format, choose Read/Write so you can add or delete files from the disk image. For Encryption, choose AES-128 (Recommended). Now click Create. You'll be prompted to create a password for your disk image. You can come up with your own, or let the Password Assistant help you by clicking the key icon. Uncheck the "Remember password (add to Keychain)" option.

Also: Don't forget or lose the password to your disk image, or you won't have any way to access its contents.

Click the key icon to call up the Password Assistant, which can generate an unlikely password to protect your file vault.