I just got one of these:
http://www.ebay.com/itm/371281044075...%3AMEBIDX%3AIT
I haven't had a chance to mess with it much. My setup is a bit different though because I'm using an HTPC so I'm trying to figure out what source resolution works the best, but it does seem to work OK. It seems to cut off the left and right sides of a widescreen image, as opposed to letterboxing the image.
I might have more feedback as I use it a little more. Since this "proof of concept" seems to basically work, my next step is to get an HDMI splitter so my source goes to my big screen and to my vintage TV simultaneously. That's when I'll have a better sense for how much I like this device. Also bear in mind that I'm using it for a 1956 B&W TV so what seems like a "quality converter" for me may be somewhat different than what seems like a "quality converter" for a 2003 TV.