Whats the best thief protection device available?

[gizmo83]

yeah i heard that autolock is pretty good. but what do u guys think about that keypad thing at http://www.qkits.com/serv/qkits/vel...pages/SP150.asp ?
is it worth it? or would a theft be about to bypass it to easy? even if so, im thinking with a really really good car alarm, an autolock, and the keypad... any theft will either not bother trying, or try and spend a good amount of time risking to be caught.