tivo hd with comcast planned upgrade to hdtv

Maybe I'm having a senior moment(s) ?



I just purchased my first HD tv.

I have a TiVo HD unit with a Comcast cablecard, since 2009.



Currently, I can record Comcast HD channels and watch them on my non HD tv.

Will I get TRUE HD from my TiVo HD unit to my new HDTV ?

Comcast says I need to upgrade to HD service.

But I think I have HD through my Tivo HD unit ?



Will an upgrade to HD service from Comcast require a new cablecard ? A simple switch at the Comcast home office ?



Why pay approx. 10/mth more if I get HD quality through the TiVo HD unit