[Jeffhs]

The cable system here in my area near Cleveland was Comcast for quite a while, then they became Time Warner Cable. I was not aware that Comcast's signal quality has gone down since the DTV transition -- even, as you say, with the high-end HD cable box you have. I would think that if that box is indeed Comcast's TOTL HD cable box, it would actually produce a better picture (not worse) than analog or pre-HD digital. Have you tried having the box replaced? There might be a problem with the box they originally installed.

I agree with old tv nut in the Chicago area. If you can get Seattle/Tacoma TV stations over the air where you are, by all means go with the ATSC->NTSC converter box/antenna combination; you may and likely will get a much better picture than you would on cable, especially, as you mentioned, if Comcast's HD quality is worse than that of its analog service. I understand that in a lot of cases OTA DTV actually looks better than DTV on cable, due to compression and other modifications DTV signals undergo on many cable systems.