Have a look here:
http://www.silicondust.com/support/channels
Once you've selected your zip code, it will tell you what you have via ATSC over the air, and ATSC-Qam through your cable companies.
I have some scripts which use this to build a channels.conf if you'd like..
Any chance I could get hold of those scripts to build channels.conf?
I'm now in Portland Oregon, zip 97224
Thanks Simon