We just heard about wireless security systems. They can be used in conjunction with a monthly service like that offered by ADT or without. We started checking these out when we saw a simple wireless window alarm at Home Depot. So, we can't vouche for the effectiveness of such systems, since we have not used one in our own home. But we're intrigued that the possibility of installing a system looks pretty easy with these wireless alarms available. One of the better sources we've found online is here. It looks like most systems run from $150 to $300. Has anyone any experience with something similar?