Do you NEED an HDTV when everything goes digital? No. Digital and HD are two different things - I get several digital SD channels on my antenna today....
I'm more than a bit surprised at some of the stuff posted on this thread.
1) I take a bit of an issue with the statement that "Digital and HD are two different things." Better to have said "HD and SD are two different things." Both are digital. HD is digital so HD and digital can't be two different things, depending on what you mean by "different."
2) The original question was whether you need an HDTV when everything goes digital. The correct answer is very simply "no" (as correctly stated and quoted above).
3) So, what do you need if you don't have an HDTV? Well, you'll need a digital tuner because your analog tuner won't work anymore since there will no longer be analog signals to tune.
4) If we are talking strictly OTA here, then you'll need a digital set top box (digital tuner) like the Samsung TS360, Samsung H260F, or the Voom box. Since you don't have an HDTV, your TV won't have a digital tuner, so that's why you'll need a digital tuner.
5) Your digital set top box (STB) tuner will be capable of giving you top quality TV on your old analog set no matter what. You won't be able to watch actual HDTV (cuz you need an HDTV to do that!) but you'll get the best TV you ever saw on your old TV for sure. All you need do is get the output from the STB to the TV. How to do that? Read on.
6) I'm using the oldest style analog TV you can deal with, and that's one with only a coaxial cable antenna (or cable) input at the back. There are no RCA cable connections at the back of the set. I'm also using a Voom box as my OTA tuner (STB). The Voom happens to have an RF coaxial cable output, so that makes it pretty easy. I just run some coaxial cable from that output on the Voom to the back of the TV, make sure I have selected channel 3 (or 4) on the little switch @ the back of the Voom right by the RF out connector, tune my TV to channel 3 (or 4), and viola', I'm watching super TV.
7) Now, some STB digital tuners don't have an RF coaxial cable out connector. But they ALL have the yellow/red/white RCA connections. So in that case, if you have an old TV like mine, you run your yellow/red/white cables from the STB to the yellow/red/white inputs of your old VCR, set the VCR to AUX, connect the VCR coaxial cable output to your TV (just like you do when you're using your VCR as a VCR) and your VCR acts as an RF modulator and viola', you're watching super TV
8) If your older TV has the yellow/red/white RCA connectors at the back, you don't need your VCR. Just connect your yellow/red/white cables from the STB to the yellow/red/white inputs of your TV, and viola', you're watching super TV.
9) Now, that leaves just the issue of "picture format," or, will I be watching a letterbox picture, a picture with black or gray bars on the sides, a picture with black or gray bars top and bottom, or what? The answer is: it depends. Most (if not all) STB's provide for setting the picture format. So you will be able to watch whatever "style" picture you want by simply selecting the setting of your preference. I have that ability with my Voom box via the "picture format" setting. Having been using this box for 10 months now, I've found that the best way to handle this issue is to select the setting that best suits the program's broadcast format and my own preference. It's complicated, but at this point it time it appears that broadcasters are broadcasting stuff without much consistency between different broadcasters. So some stations broadcast their SD stuff so that you get everything in a full screen 4:3 format with no distortion, etc. Some stations broadcast such that some stuff is full-screen and some things aren't. Stations that broadcast some HD programs will give you the anamorphic widescreen HD format (letterbox, but not the little letterbox) for their HD, and then black bars on the sides for other non-HD stuff, like commercials (or some commercials). This is something you'll just have to live with until you spring for an HDTV.
The point is, you will not be locked into watching any particular picture format. You can select whatever format you prefer by fiddling with your STB's picture format feature. Up until recently, I'd been leaving my picture format setting pretty much set one way and living with whatever the broadcasters were giving me -- even if it was annoying black bars or images that were distorted (people stretched too tall, etc). But now I'm changing that setting as required for each show I'm watching -- if I have to. So now I'm no longer watching any black bar shows or shows with too-tall folks. The downside is that I'm constantly changing that setting as I go from show to show. But there's nothing I can do about that as long as I'm too cheap to get a new HD 16:9 format TV and continue to live with this old 4:3 format TV. BTW, "format" is more properly termed "aspect ratio."
So, "no," you do NOT need an HDTV to watch digital TV.
You WILL need a digital tuner (STB) and a way to get that tuner's output to your particular TV, which should NOT be a problem at all and WILL NOT be a problem at all for anyone with a working VCR to use as an RF modulator (if you need it).
Any questions?