Is the decoder, any decoder at all, able to work with any card. When I took out a Sky subscription, they sent me a card; no, not a birthday card but a subscription card that gets slotted in the front of the machine. This tells the decoder I've got a subscription and allows it to unscramble or DECODE the incoming signals. Am I basically right so far? Onwards; would any other fully paid up card of the right physical dimensions etc, etc, connected to a suitable dish etc, etc, work properly. In short are cards and decoders compatible from different companies as long as all other criteria are met