Whats the best software Laptop Alarm system?

I'm looking for a deterrent to stop someone picking up and walking off with my laptop.

This is to keep a house guest from stealing the computer when the wife and I are asleep. The laptop wont be left unattended in strange places outside of the home.

I have seen apps such as Prey http://preyproject.com/, LAlarm http://www.lalarm.com/en/index.htm and even paid for services like LOJack for Laptops http://www.lojack.com/pages/laptop.aspx.

Of the free apps which ones do you think are the best? ( even apps I didn't mention, you may know of better)

I appreciate any advice. Thank you.



Food for thought

Since this is one of the nets most popular security forums I would expect talk about such apps and devices to be popular here but a search didn't turn up much. I think Wilders is missing a huge part of computer security and should create a forum devoted to this topic. How can Wilders be a security forum without taking into account all forms of PC security? Seems Wilders is sadly lacking on the theft issue.