In the time it takes to read this, all your critical computer files could be riding down the road on the key ring of that lead carpenter you just fired. Yes, it's important to protect your computer data from hackers, spyware, viruses, and other network attacks, but it's even more important to think about the physical security of your data.

Lock down. If a thief steals a laptop or an external hard drive, he or she also gets whatever data is on it. Secure laptops and other peripherals at your office, jobsites, and even on work trucks with cable locks such as the popular $45 Kensington MicroSaver (www.kensington.com).

Batten the hatches. Treat physical access to your computer equipment, especially file servers, with the same care you would your safe deposit box. Keep the door to the server room locked, restrict who has access, and closely monitor anybody asking for the key.

Cable your dongles. Specialized software often requires USB or printer port “dongles” plugged in to run. I've seen instances of disgruntled employees ripping off a dongle on their way out the door, making it impossible to open CAD files or run the weekly payroll. You can prevent dongle theft by threading a thin piece of aircraft cable through them and bolting the cable directly to the computer case.

Remove removable devices. Tiny solid-state USB “thumb drives,” external hard drives, and CD-R/DVD-R disks represent opportunities to lose data through theft or carelessness. Did you know that an Apple iPod music player can be used to lift files or load unauthorized software? You'll never stop people from bringing these things to work, but you can often disable or permanently cover the USB ports they plug into. Likewise, disable any recordable CD or DVD drives, or don't buy employee computers with them installed in the first place.

Handling handhelds. PDAs and “SmartPhones” also can contain large amounts of sensitive information. It's almost impossible to physically secure these devices because of their small size, but software such as JPMobile's “SureWave MobileDefense” ($30 per user, www.jpmobile.com) will add encryption and a secure login to access data, and even permanently delete information on the device after a number of failed login attempts. It's available for Palm, PocketPC, and RIM Blackberry PDAs. —Joe Stoddard is a process/technology consultant to the building industry. Reach him at www.mountainconsulting.com.