I can't speak much on the HD front, because I don't have it, but I can say that what the tech said is true. Years ago, when people had mostly RG-59 (cheapo cable) running into their homes, I used to tell my customers that they can get a 75/300 ohm adapter (cable jack on one end, two wires on the other) and hook their cable up to their stereo systems to get better reception, and it worked. The downside to this is, the cable also picked up signals that you DIDN'T want, which would interfere with a good cable signal. Nowadays the cable is much more heavily shielded, so I would tend to agree with the tech: It's absolutely possible that you're getting an OTA signal, but that also means you have older, low-quality cable.

It sounds like you have an older dish box that modulates the sat box output to channel 3/4 on coaxial. Then when you turn off your sat box it passes through the OTA signal. To record both, you will need a converter box that has an analog tuner (NTSC for the sat box output) a digital tuner (ATSC for the OTA) and has an output format supported by your dvr/vcr. The simpler solution maybe to get a newer box for Dish that has the right output.

The truth is that most cable companies including comcast are moving away from analog and clear QAM signals. So even if your TV has ATSC tuner there are few or no unencrypted channels available. You will need a box to "decode" the encrypted digital signal. In my local area comcast offers a "free" (for 3 tv's) tuner that outputs a wretched analog via channel three signal over coax signal. Think back to VHS quality days. For about $10 - $15 per box per month you can get a HD box that outputs a variety of digital and HD signals. The only other option is called Cable Card, a cable card is a small card that allows the decryption of the cable co's signal. Few if any TV's now have cable card slots (unfortunate!). There are cable card devices out there and your cable co is required by law to support them. Some examples of cable card tuners are Tivo Premiere, Moxi DVR, Computer based cable card tuners (Silicon Dust, Ceton, and ATI). This option allows you to own the tuner and rent for small fee the cable card. The cable co. wants you to have a box on every tv, it gives them control and allows them to up-charge for HDTV. There are a few options for "sharing" boxes between tv's but none that are compelling nor do they work well. Some of the sat companies boxes are designed to be shared to multiple tv's.

I bought the Panasonic DMR-EZ37VK DVD-Recorder/VCR Combo with ATSC Tuner. I needed the tuner feature because I get my TV signal from an antenna, not from cable or dish or other digital source. I paid $230, minus $75 in gift certificates from Amazon, thanks to my Amazon credit card. I notice the price is up to $260 now. The reviews on Amazon (only four of them) aren't that great, but I saw better reviews on other sites. I researched this purchase ad nauseum because of the antenna thing. I started out at Circuit City, where I discovered some of the salesmen understood my signal situation and others didn't have a clue. I guess antennas are too antiquated for some young men to even acknowlege them. :-) Not many models can accommodate the antenna signal, and you probably don't have to worry about that feature. I learned in my research that Samsung is rather highly regarded, along with Panasonic and (of course) Sony. And probably others I haven't mentioned. Yes, I like the unit  although I haven't tried to record TV programs on it yet. It's not even hooked up to the TV, because I'll ask my DS to do that for me after Christmas. Right now I'm copying VHS tapes on it to give to my kids for Christmas. It's been doing a nice job. Soooo......are you shopping for one?