The simplest way to keep your computer from disappearing is to lock it down with a cable. Most laptop computers have a security slot that can hold a cable, while desktop computers often require a special plate that attaches to the side of the computer, monitor, or desk (see Figure 20-1) with glue.
Security cables, like bicycle locks, can deter novices and probably slow down opportunistic thieves, but they can't stop determined ones. Given enough time, ordinary nail polish remover can dissolve the adhesives used to glue the cable attachments to the computer, and laptop security locks can be broken with a few well-placed blows from a hammer. As a faster alternative, thieves may just snip the restraining cable in half with a pair of wire cutters.
Besides locking down your computer, make sure you lock any doors and windows that can allow access to your computer in the first place. The more barriers (motion detection alarms, guard dogs, strong door and window locks, etc.) you put in the way of a thief, the less likely a thief will want to overcome all of them.
For further protection against theft, make sure you record your computer's model number, make, and serial number in a safe place. Then if someone does steal your computer, you can enter the stolen computer's information into the Stolen Computer Registry (http://www.stolencomputers.org), a free service that maintains a database of stolen computers. If someone finds your stolen computer, the Stolen Computer Registry can help get it back to you.
For additional protection, use an etching pen to scratch your driver's license number or other identification on the inside of the computer case (where thieves won't likely find it) or on the outside of the computer case (to reduce the value of the equipment, since the thieves must remove that identification before they can resell it).