The official word on early termination fees, which you'll likely be subject to: http://forums.xfinity.com/t5/Billing/Early-Termination-Fees-ETF/m-p/2895117#M96760
Basically, if you're in a contract and cancel early, you incur a fee unless the contract says otherwise.
Hi emiller586, the information that (Welcome_to_Post) shared is correct. If you're still within your contract agreement and you move to an area that is not within the Comcast footprint, you will have to pay any early termination fees associated with your services. Please reach back out to me here if you have any further questions.