When i said that "nothing beats native vga", i was only referring to the xbox, and not the 360. HDMI and DVI will generally give a better quality image. But the xbox only supports analog video, so anything digital is a moot point. Native VGA, only possible with Frosty's vga bios on a modified xbox, and the vga bios do not work with 1.6 xboxes, is the best possible video signal found on the xbox. VGA is better then component. And the xbox only supports 720p and 1080i HDTV resolutions; not 1080p. And 99% of xbox games only support up to 480p, so it will be impossible to play them at any higher HD resolution. Many applications for a modded console do support 720p and 1080i, though. For example, XBMC.
360 A/V questions should be posted in the appropriate 360 A/V thread. The only way a HDMI to DVI cable will work on the 360 is if your 360 has an HDMI port. That cable will work if you have an HDMI 360. And by all means if you get an HDMI 360, use an HDMI (or HDMI to DVI) cable with it for the best picture. Do not use a transcoder (x2vga2) when you can get true digital or true vga out of the 360. Both native HDMI and native VGA are better then the x2vga2.