Capturing HR HDTV?

[drj]

Does anyone know how the latest HR HDTV avi files that you see on torrent sites are made? They all have a resolution of 960x540 and the quality seems amazing. They seem to be encoded in XVID. I was just wondering if there is a way to capture video onto a computer in such great quality, or does this involve a multi-step process of capture and then conversion / encoding? Any tips would be very appreciated.