I am pretty sure that it's simply a case of reconnecting the battery and it should work. Do other electrical systems work, lights, wipers etc.
Have you had a look at the starter motors? Once my mates car would not start and he was just getting a click yet the car would jump start and it turned out to be a fualty starter motor. Yet it seems strange this could happen on both cars.
It may also be worth checking that you have a good earth, you will need a multimeter, select DC volts (you may have to adjust the range) and connect one probe to the positive teminal + of the battery and the other probe to any earth point on the engine/chasis and you should get around 12.5 V give or take depending on the condition of the battery (engine off).
Last edited by andywhitehurst; 24-05-2005 at 20:58.