There was a storm outside. It is well known that crooks strike when it rains. The best solution I have come up with for this dilemma are
http://scratchpad.wikia.com/wiki/InfraRedLeds stacked around the home connected to CAN bus or RS485 network. CAN seems to be preferred becaus it takes care of the physical and coms layer. RS485 is just physical layer.
Especially if it rains nobody was supposed to be walking around the house. The criminals infiltrate an neighbourhood and then jump over the walls. Wall perimeter breaching detection should be implemented.
Those IR beam stuff alarm companies sell for R500 is a scam. A bog standard industrial solution (what do you think factories use? ) has been available in an IC package the TSOP1838 Used in IR barrier circuits TSOP1838 , TSOP1738 (38khz version)
http://www.digchip.com/datasheets/quote.php?action=search&pn=TSOP1838. These electronics magazine articles show how to configure them
Elektor Electronics p.55 and p.19 July/August 2002
Infrared transceiver - Elektor electronics Jan.2002 p.62
LIke a marine in a warzone you would have to know what moves around you at all times and still be able to carry on with your life. IR led barrier beams (hundreds of them) stacked around the house and wall, roofs , gutters will do the trick.
The problem of dealing with
insurgents jumping over walls can easily be dealt with, it is just a matter of getting the circuits and code on the Internet and explaining the technology to people, making home automation a generic concept.