totally agree...but will undercover works if the mac is reformated straight away?

If you're looking for some sort of tracking...
the answer is Orbicule's Undercover.
Their website explains everything: http://www.orbicule.com/undercover/
give it a read.

I got this for my 13" MBP the moment i got it.
But for maximum protection, it doesn't stop there.
I enabled the firmware protection, which requires a password to enter the boot menu so you can't reformat or even boot from a different partition. I don't know what happens if you change the hard disk though but I think it won't even allow the new hard disk to be used?
I enabled the option in the security preference pane to "request password 5 mins after sleep or screen saver begins". Of course that means u should have a login password.
Since the Undercover software works by tracking the user while online, I need to enable the thief to be able to use my mac. So I enable fast user switching and created another Standard Account (NOT admin) for the thief to use which doesn't have a login password. I also locked down my personal folders/home folder and can only be accessed by me. So in the event my mac gets stolen, the thief has no choice but to use the Standard Account I created and can do pretty much any basic thing except anything that requires admin access. He can't access my folders but he can use every bit of the remaining available space for his own use.
Then hopefully, in due time, I will be able to track that bugger down. And hopefully he/she ain't a tech geek.