For those of you that have done low cost (consumer product) motion sensors,
the type that turn on lights when people enter the room etc....
 
what do you recommend?
I'm currently looking at a Hamamatsu  Pyroelectric detector,
what about IR?
what else? 
 
What's the easiest (lowest parts count) method?
 
Thanks......
Jason Wolfson
Lipidex Corp.