So rummaging through my bins I came across one of these. Seeing as how they sell for like $60 and I really hate the xbox I decided to test to so I can sell. I was curious though on the difference in quality. So I ran some test. It was quite apparent that this High def, has more vibrant colors and you can see in the background the squares and hexagons show up better in the High def. Soon as the xbox starts you can just see the logo has brighter and sharper images.
After seeing the quality difference, I may have to keep this.
Both tested on my 27" KD-27FS170 Trinitron.
Here is a normal standard a/v cable.
Here is the High def. pack