HDTV channel from Basic cable?

I have only just bought a HDTV. I connected the Comcast basic cable to it and run the channel investigate. Then I can watch some channel like 2.1, 5.1, 7.1, etc. They are thoroughly clear. Am I receiving HD channel? I have thought to acquire a HD upgrade from Comcast. So seems I don't hold to, right? Thank you for your time.
Answer:    OH THOSE ARE HD CHANNELS my friend...that you can believe....


So don't let these others FOOL YOU....

But here's the problem....you ONLY enjoy LOCAL HD TV stations and you're missing the Benefits of the Box.....the HD CABLE BOX....

Discovery channel, Science Channel, Animal Planet - HD, TLC-HD, Fox HD, ESPN -HD FOOD -HD HD Net....and a few others that I can't remember or don't consideration to.....

It's not a lot of channel. at least until 2012 but it's progressing
How do I re-seal a tube tv?
probably not HD probably merely your TV making the regular channels look nicer