Breakdown of the Cables to get the Xbox360 to go HD
John Breakwell, over at the MSDN blogs (I am subscribed to the whole MSDN blog group), has a really good breakdown of the Xbox 360's HD capabilities in regards to the type of cable you use. Since the 360 only supports HD through the component, and VGA cable, he broke it down in a chart for those two cables.
(The chart is from John's blog post)
Thanks again John. You can head over to John's blog here.