OTA (over the air) is the way to go if you are in range. Check your address at www.antennaweb.org to see, the user interface ain't the greatest there but it should make sense eventually.
But Worm, I think you seriously misunderstand what's up with the comcast box. One common error people make is to confuse Comcast's basic digital cable box with high-def, to get high-def you have to spend $3 more on top of the $5/month fee for digital cable. With just digital, the channels are either analog (channel numbers under 100) or standard-def digital which is approximately DVD-quality. But, the extra $3 and the high-def digital box will get you access to all of your locals in high-def and a couple of other basic level ones, plus if you sub to HBO or Showtime then you will get the high-def versions of those channels as part of the $3 fee.
In either case, the coax line is quite capable of carrying digital signals, after all if you have a cable modem it plugs into the same coax and it is obviously digital only. On the other end, running component video to your display with a high-def signal is signficantly more than just blush on a pimple, whether it is with a comcast-hd box or a satellite-hd receiver or an OTA high-def receiver, the majority of current HDTV owners use component video to get the picture to the display and it still looks awesome. One way to think about it is like a CRT monitor on your computer, CRTs have long been able to do resolutions higher than the highest high-definition resolution, but they use an analog VGA cable which is essentially just RGB+sync and can be converted to component video pretty easily (I have a $100 box designed just for that purpose). If a computer's analog display can look as good as they do, so can the analog output of a cableco's high-def set-top box.