I've been running my MCE HTPC for about a year now. I love it. I went OTA in October. So far, I'm very happy with the entire setup. I kept my rogers subscription because the I like some of the 'specialty' stations they have. I used to use the Avermedia card, but decided to go with a DViCO Fusion HDTV5 USB Gold tuner instead. It can do QAM and ATSC.
Personally, I would highly recommend an HTPC because of all the other stuff you can do with it. DVD Player, MP3 Player, Movie (AVI, Divx, etc) player, Internet browser, etc. My excuse is that it makes my TV investment go further. :D
If you're interested in building an HTPC, visit these guys:
http://mcehq.sensuz.comI saw them at the Markham Home Show back in October. They were running a demo with their MCE system with an OTA setup. I didn't buy one of their systems, but I got most of my equipment from them.