What's the best laptop recovery system?

There are two services offering help in tracking a stolen laptop. One is Hidden (http://hiddenapp.com/). One is Prey (http://preyproject.com/). Both have had recent stories of people who recovered their laptops using the tracking software. Does anyone have any informed opinion on which one is better? And can you use both of them? You know, belt and suspender approach. There may be other options I am not aware of.