[updated:LAST EDITED ON 09-Aug-02 AT 01:20 PM (GMT)]If you want to be cheeky, then cancel your sub just before leaving your old house.
then at the new house start a fresh subscription. You might need to use a different bank account, or your wife / partners name. Then you will get a new digibox and dish installed, and you get to keep your original digibox (and dish if you choose to take it with you). You can use the second digibox either for FTV, as a spare or for £12 can get a mirror of your main subscription.