How to tell if a laptop has been used of off the normal network

You could probably combine prey with a script or to to accomplish that.

"Wow, a lot of fairly complicated answers here. How about this:

It's probably assumed that a mobile user who takes his\her laptop home shuts it down when leaving the office and turns it on at home. Look in the event log (System) on the laptops and look for system startup events. If you find startup events outside of the normal working hours you can assume that either:

There was a power outage at the office.
Windows Updates has rebooted the laptop.
The user has taken the laptop home and used it from there.

Granted this is not foolproof, but if you find no system startup events outside of the normal working hours then it's probably pretty safe to assume that that user is not taking the laptop home."

"Hardware may be the simpler answer.

Remove the batteries and see who notices. And/or remove the wifi pci card.

Other options include a small dab of rubber cement between the laptop and docking station, it'll pull off easily still, but you should be able to still tell if it's intact."