Originally Posted by blueiedgod
Only if you need to connect additional TV's using their service.
I believe that's what it becomes once the DTA is replaced with customer provided equipment and a cablecard. It's best to contact Comcast to get clarification of their pricing policy.
With a single CableCard in a Windows system you can decrypt 6 streams (with approproate tuner) and then distribute them your self over the home network, without having to pay for additional boxes, or outlet fees.
You literally only need one cable drop, to connect to the tuner, and the rest can be done over network..
The OP is asking about cablecard to replace a DTA on one TV. If he/she is interested in building an HTPC and networking that is always an option (and probably more expensive than a DTA or cablecard). But..... if interested, that should perhaps be another thread.