If they can squeeze through that window, they can take whatever they want. My deductible's only $500 and anything they're gonna grab is going to be worth either more or less and can be replaced for less than the price of an alarm.
Stupid is as stupid does. If you're like my friend who left a radar detector on the windshield of his brand new Saturn in downtown Kansas City outside a strip club called "Bazooka's", you kinda half to know there's a possibility it could get jacked. What really cracks me up are the people who have a nice aftermarket stereo, but forget to take the faceplate with them or at least hide it. Hellloooo!