Eventually this sort of device should be readily available (it's part of the requirements for migrating from analog to digital for TV broadcasting, to allow existing analog TV's to still receive broadcast TV signals). The only thing I know of now is an over-the-air HDTV receiver. These receivers generally include composite and s-video outputs that will work when the receiver is set to 480i mode, which allows you to record HD broadcasts to a VCR - or feed the signal to a standard definition analog TV. HD receivers have come down a lot in price - I found
this Zenith unit on eBay for $180. For this to work, though, he'll need to have decent digital reception, which may require a different rooftop antenna. And since most stations broadcast both analog and digital signals from the same tower, I wonder if the digital signals will come through any stronger than the analog signals?