get rid of the alarm system ? keep it, just don't turn it on ?
i have a friend whose parents had an alarm system like that, once a spider made a nest in one of the sensors and it went off in the middle of the night and woke everyone up. (further proof that spiders are evil). (actually, once i was spending the weekend there and didn't know about the alarm, and got up in the middle of the night to get a drink of water, and his mother heard me in the kitchen and came running down the stairs to turn off the alarm before it went off and scared me half to death).