Can I improve the quality of my Comcast basic cable SD TV to 480p or better?

Honestly, there isn't TOO much you can do without some sort of pc-based solution. Your friend is partially right, but there are drawbacks. You can build a http://www.mythtv.org/ box with whatever tuner you want. You'll need a card that does both qam tuning and analog tuning. Analog mappings are cake. Digital, notsomuch. The channels move a lot, they're a pain to keep up with, and unless you don't care about guide information, this alone (at least to me) makes it worth it. If you want a more in-depth explanation, just ask. Nothing, absolutely nothing, aside from signal strength and lack of noise, can make an analog picture better. Not a special tuner card, not a magical line insert, not even He-man, can improve analog signal. A lot of HD broadcast channels are encrypted, just like the SD digital channels. You'll get a few HD signals, but not many. Then again, with subscribed digital cable, you also won't get many HD signals, as there just plain aren't that many. What confuses me is the fact that you spent a grand on a TV but won't cough up 5 bucks a month for a 6412.

Cancel your comcast service and just get an OTA tuner and a decent antenna. I get 16 digital channels over the air. I have a MCE PC and just bought a $100 HD tuner card to get HD channels. I havent had any problems with reception, however you may want to check antennaweb.org to see what kind of antenna you need.

Thanks meehawl and onedarkride for helping me sort this out. You have both given me plenty to look into and get the ball rolling. What confuses me is the fact that you spent a grand on a TV but won't cough up 5 bucks a month for a 6412 Well...maybe I'm an idiot? Lol, honestly, we're avid Netflix users and the monitor we got is great for DVDs, but we just don't watch that much TV, and what we do watch (Comedy Central, PBS, whatever's-on-after-the-kids-are-in-bed) doesn't need to be HD. When I looked into this a year ago when we got the new monitor, I thought the price differential between Basic cable and HD programming was much more than $5/month. If that's all it is, and there aren't a lot of secondary and/or hidden charges, I'll place an order today. I certainly didn't realize it was this cheap.

Well, I just called Comcast to find out how cheaply I could get local channels in HD (in Seattle). The helpful phone person told me that HD reception cannot be added to Comcast's cheaper service plans, and that the cheapest plan which would give me locals in HD would run some $50/month. She also told me that I could not add comcast DVR service to the cheap plans either. And thus disappears any incentive I might have to dump DirecTV for Comcast. So I'd take that "$5/month" which a handful of salt. YMMV.

and what we do watch (Comedy Central, PBS, whatever's-on-after-the-kids-are-in-bed) doesn't need to be HD FYI, and this may help sway your decision, Comedy Central does not broadcast in HD anyway, and as near as I can tell they have no plans to do so in the immediate future. The HD stuff from Comcast is indeed $5 a month, but that presupposes you're already on a digital box with a silver or platinum package - if you're not, it's closer to carterk's $50 a month estimate, and an extra $10 if you want the DVR.

FYI, and this may help sway your decision, Comedy Central does not broadcast in HD anyway, and as near as I can tell they have no plans to do so in the immediate future. The HD stuff from Comcast is indeed $5 a month, but that presupposes you're already on a digital box with a silver or platinum package - if you're not, it's closer to carterk's $50 a month estimate, and an extra $10 if you want the DVR. Yeah, I know for a fact that we only have basic cable now, so I'll need to see what the price jump will be, talk to my wife, etc. , which I won't be able to do that for a few hours. Also, we live in a very hilly area, so OTA antenna reception is notoriously crummy, and while we can probably find whatever we would be missing on BitTorrent, upgrading our Comcast account may make the most sense. Anyway, thank you all very much for your help in bringing me up to speed with the technical limitations of what I want to do. I don't know if I can pick a single best answer, but I greatly appreciate everyone's contributions to this thread.

Even if your analog antenna signal is crap, you might want to give the digital reception a try. With the right http://www.hdtvprimer.com/ANTENNAS/comparing.html/http://www.google.com/search?hl=en&q=cm7777&btnG=Google+Search/http://www.avsforum.com/avs-vb/forumdisplay.php?f=25, you can get very good results. If it's a station you want/like, the results are marvellous. It's either well-nigh perfect, or it's just not there. There's really very little in between, no http://www.kyes.com/antenna/propagation.html, etc. If you have a bunch of hills you probably want a receiver good at "multipath".