Hmm
This doesn't sound quite "alarm-ish" to me; try varying that same high note at different amps(I think), and adding other alarm effects (like what you'd hear in a jewelry store or when the fire dept gets a call or when someone leaves a retail store with the plastic thing still on the product; that kind of gist). Make it more of a(as the title suggests), "They've broken in, we've gotta get 'em!" sound. HEH, but not entirely bad.