>  I installed an alarm in my van but didn't hook up the shake sensors. I can't
>stand hearing alarms go off every time a Harley goes driving by.

I had a Radio Shack Tandy alarm in my T2 for a while, but turned the
motion sensor off too.

>  In the end I think the biggest deterrents are ... not having
>anything visible to steal.

Unfortunately this is very often utterly impractical...