converting widescreen and HD down to SD for old tv's

[richms]

If I set my sat box for widescreen output, then I cant use it on my old tvs, if I set it to letterbox or pan and scan, its unusable on the new TV's, since I cant get any HD output when like that.

Is there a box (preferably with HD component in) that will allow selectable letterboxing or pan and scan of the content onto a normal composite output.

I have seen converters like 130394510072 on ebay, but the answer to that other guys question gives me little faith that they really know what they are talking about, and I have a feeling that all it will do is make a widescreen pal/ntsc output, so really no better than taking the composite out from the satillite box in anycase.

Would be great if the box could detect when its on one of the few remaining 4:3 channels and not change the aspect at all, but I am hoping that sky tv NZ will get their crap together and start pillar-boxing those channels since watching things in fatto-vision is quite annoying.