One of the unfortunate consequences of using a portable machine, such as a laptop or a netbook, is the ease with which someone can walk away with your valuable data. It’s not just thieves hanging out at your local coffee shop you need to worry about — your own busy life can put your computer at risk; a recent survey revealed a staggering 12,000 laptops are left in US airports every week.

Losing your machine can be pretty devastating, but a little bit of forward planning could mean your files don’t fall into the wrong hands and maybe even assist with recovering your computer.

Prey is a free, open source service for Windows, Mac and Linux, designed to be unobtrusive with a very small installation. Simply download and install the application on your machine, create a free account, then log in to the Web site to manage your settings.

Prey offers a wide variety of tools to help you keep track of your system’s whereabouts, usage, and can even help you discover the identity of the person who has possession of your machine.

While it is true that more tech-savvy thieves may simply reformat your system, thus rendering Prey useless, the urge to snoop around your files for valuable information often proves irresistible. There have been some successful prosecutions and laptop recoveries thanks to similar services.

The features in Prey easily rival commercial alternatives such as LoJack, but without the monthly fee. The Web interface allows you to mark your machine as stolen, then offers a variety of remote options for keeping tabs on it.

The application stays resident secretly in the background on your system, allowing you to then control the information it sends back to the Prey servers. When your notebook is reported missing, Prey will attempt to connect to the nearest open Wi-Fi hotspot, and then send back regular reports. You can remotely check various statistics, such as current running applications, a screenshot of the desktop, and even take an image with the built-in webcam and upload it to the Web.

Geo-location is an invaluable feature of this service; the current location of your machine can be shown on a map by using Wi-Fi triangulation, or more precisely if your computer has a GPS device built-in. The Wi-Fi location is surprisingly accurate; my Mac lacks GPS but was pinpointed to the exact location on my street.

You can choose to make the missing status of the laptop known by controlling various alarm options in Prey, including audible alarms, and popping up requesters on the screen asking for the current user to contact you to return the machine. These options could be useful if you know the machine is simply missing rather than stolen intentionally, but probably not recommended otherwise, as it just gives the thief an excuse to wipe the machine immediately.

Obviously, the usage of these kind of applications ends at remotely stalking your computer. After using Prey to locate your missing notebook and taking a photo of the thief, it’s then up to you to speak to local authorities and convince them to take you seriously — tracking down the offender personally is obviously not recommended.

Regardless of the real-world effectiveness of these services, it’s one extra glimmer of hope that you otherwise wouldn’t have. Since Prey is a free application and extremely lightweight, there really is no excuse not to install it — one day it might prove to be invaluable.

Dan Wood