Some info on CableCards here:
http://customer.comcast.com/help-and-su ... ablecards/
Some info about installing them on a Tivo here:
http://support.tivo.com/app/answers/detail/a_id/135
Unfortunately I think the idea of CableCard ready HDTVs died - I can't find any doing a casual Google search so your two options would be a Tivo or Media Center PC with a CableCard tuner.
Also refer to the post I made recently about my recent purchase of a USB CableCard TV tuner for my Media Center PCs:
http://pcabusers.org/forums/showthread.php?t=54814
I've been using Media Center PCs as my DVRs for 10 years now. However up until recently I still rented a box from Comcast for each PC and then connected the box to the computer through a tuner card, and the computer controlled the box with an IR emitter that simulates the cable box's remote control codes.
The CableCard tuner let's me eliminate the boxes entirely.
I'm a techie and I love media Center, but the least painful route would be to buy a Tivo. Tivos make Comcast's DVRs look like crap. Only thing is that Tivo has a monthly subscription for the channel guide ($15 I think). No fees for the channel guide in Windows Media Center - it's free.
I don't know much about them, but I have friends who have them and I've played with their units when visiting. Some Tivos here on Amazon:
http://www.amazon.com/s/ref=nb_sb_noss_ ... words=tivo
A good article here:
http://venturebeat.com/2013/01/10/the-g ... xperience/