If you use that system, you'd have to run wires from the sensors at the washing machine and dishwasher back to the control valve.
There is a device called Water Cop which uses sensors attached to wireless transmitters.
There is yet another system, much more expensive, which uses NO additional sensors. It reads the main water flow and if it sees a sudden increase in flow rate, it assumes there is a leak somewhere and shuts down the supply for the whole house. I can't remember the name, nor can I find it when I search - but I'm sure one of the pros here will help us out.