Your HDTV will up-convert any standard def video you feed it to it's preferred internal format. This does count as "HD".
But standard def video was designed to fill a nine-inch screen. There is only so much you can do to 'magnify' this to fill a HD display. So it's basically 'magnified' to create a HD image.
Some DVD players like "Up Converting" or "BluRay" or HD-DVD will do a bit better job of the up-conversion. But you must use an HDMI cable to get this feature.