No Problem! DISHTV is digital and direct, that means when you choose to install DISHTV, you need not disturb your cable connection, just install your own Dish, simply connect the set-top box to your existing TV, insert your personal unique Viewing Card and you are ready to go!
Infact, you can watch television without disturbing your existing cable connection in normal TV mode and DISHTV in AV mode, by choosing the AV option from the remote of your TV set. That means both the inputs can be used simultaneously.