Here is a box I have been using for a few months and am very happy with it. I use it on a LG 23" set. I use the component output. The manual shows an analog connection using the 480i output setting and a YPbPr format via a normal video output connection. Svideo available also. Never tried it. I wonder if it would output a 4x3 letterbox down-conversion.
One forum says NG for 4x3. It's built in aspect ratio converter does not change HD signals. I wonder if you ran it through a DVD recorder that does change aspect ratio displays would do the trick.
http://www.epvision.com/index.htm
I live 30+ miles from the xmtrs and in a valley to boot. I do not get all of the Phila stations as I am on the edge of the coverage area, but enough to be happy. I am using my 20 year old Winegard VHF/UHF/FM on the roof via coax with no splitters. Pure signal. I am looking at modern HD antennas with built in preamps and may try somthing inside the attic.
It does OTA and CLEAR...caps for emphasis...QAM cable signals. Of course, Comcast cannot spell the word 'clear' so it will not work with them. Some local cables are retransmitting the local digital in-the-clear so check your system.
Dave A