The immobiliser & alarm parts of your car are 2 completly seperate systems. If you are trying to repair a broken key that you have, then if the key is cheap it may be worth it. The immobiliser chip, as Chris198212 says, cannot be re-programmed. So you will have to swap that from your old key, along with the physical metal bit that is cut at the factory. The alarm board however, can be re-programmed to your car using your code card (either supplied with the car if an import, or obtainable from a dealer / decent specialist - approx £42.00) and the alfa examiner (I don't know if any of the other diagnostic kit can programme keys / alarms). So all you are buying really is the case and the alarm remote circuit board. If your remote part is not working, it may be repairable anyway.