I agree with Pitbull1K,
The trick I use for my laptop and the airport x-ray machine is to put the laptop in my roller-bag. I can't recall the last time my laptop has been checked since, while other less fortunate souls both before me and after me in the x-ray line have been "chosen". I think they focus on laptop carry bags.
Also, here is a pretty interesting article on the subject I found today.
http://www.apbnews.com/newscenter/br...er0529_01.html