Technology Bites says "Some of the effective software for this purpose are – LAlarm, Prey and Adeona. Unlike Prey and Adeona, which track the location of the stolen laptop, LAlarm comes as a complete laptop security utility. It’s a free security software that sounds an alarm when your laptop is in danger of being stolen. LAlarm triggers an alarm when the laptop is disconnected from the power outlet or removed from the table and can destroy all your sensitive data if, the laptop gets stolen. You can also get an SMS alert when an alarm goes off."
To read the complete review, see: http://www.teknobites.com/2010/04/06/how-to-remotely-track-your-stolen-laptop/
See also: What others say about LAlarm