Tracking stolen computers

Some software will actually hit the vendors website everytime the product is launched. Even if it isn't a web based program.

Also some manufatures I have seen will have a program load at startup called pinger that seems to check-in everytime the computer is turned on.

You can detect a computer on the Internet by its MAC address. But you will have to be on the same Internet segment of that computer or its destination address. Plus a clever hacker can spoof the MAC address or use a differnt NIC.

Dell assumes that anyone who comes into posession of a Dell computer will eventually connect to the Dell web site. If you can give Dell the service tag of a stolen computer, they will look for it.

HP implemented Electronic Serial Numbers years ago. (Similar to Cel Phones)

It's a litle more dificult to get arround......but not fool proof.

They also have a Web site that gives you 'as shipped' configuration information when the ESN is supplied.....which can be compared/updated when logged on with the computer your checking on.

newer laptops they are building gps into them.
that use a trickle from the battery.
so vendor can supply specific signal from serial number.

desktops ( pcs ) this would also have to be done for this simple a method.