ANSWERED (Thanks!): I want to upgrade one of my three non-HD TV Boxes to an HD box. The two other boxes can stay standard definition. How much will it cost? (And how much extra for a HD-DVR TV box) Can I just go to a Comcast store and swap the boxes? I can't seem to find out how to do tis online and a phone call to Comcast involved a salesperson who wanted us to add more services that we did not want.
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