This is just a test of the Raspberry Pi hooked up to a DS18B20 temperature sensor. Using LadyAda's tutorial, this was up-and-running in about 5 minutes and sending out highly accurate temperature data over the network. As it is much more expandable and easy to use than the LM75, I think this will have to be the weapon of choice for the heating control system. My only concern is whether the Raspberry Pi can really be used for a 'mission critical' application, bearing in mind that today the there has been an ice storm raging across the UK which has been particularly bad here in Northern Ireland. This would not be a day to have the heating control fail due to an OS crash!