Ok, ive been reading alot on the X360 and so far, it seems like a pretty cool system. However, the biggest thing thats been confusing me is reading about how it has "native 720p suppot". Although its just three simple words, what Im still trying to get is will it only render games at 720p and scale them to the desired resolution or will it render them at the corresponding resolution desired. I ask this becasue I cant see why anyone would make a HD system that instead of rendering a selected resolution would render it at just one and then scale it. This is mainly a concern because some HDTV's (like mine) have slightly weird physical resolutions (1366 x 768), and when you scale an image not once, but TWICE, usually the final bi-prodcut is pretty junky. I could go on, but I would rather leave it at this: does it render at 720p and scale it, or does it render at the selected resolution?
The games are rendered at whatever the software was designed for then scaled to the res you are using by the ATI chip.
By default every game released on the 360 needs to run at 480i and 720p. it is up to the dev to take advantage of more.
As the XBOX is primarily a HOME ENTERTAINMENT CONSOLE (read, it connects to tv's) then most devs are only going to support the resolutions that are standard for tv.
Some games only render at 720p, then the ati chip scales to whatever resolution you have the xbox set to. Some games support multiple resolutions and are clearly marked on the back of the box.
The good news for you is that if you have the xbox set to the same resolution as the game supports it does not scale the image. The only thing that would scale it is your tv.
For example: PDZ runs only at 720p. If you have the xbox set to 1080i then it will render the game at 720p, scale it up to 1080i, then your tv will scale it down to 1366x768.
If you have the xbox set to 720p then it will just output the 720p image that the designers originally intended, and the only thing scaling the image would be your tv.
Now, a game like NBA 2k6, which supports 1080i (as well as 720p, 480p, and sdtv), would be rendered at 1080i if that is what the 360 is set to.
Be careful of the vga cables by the way. While they do support native pc resolutions (including your 1366x768 rez), they usually end up with washed out colors. Also, seeing as the devs are not designing their games with the off the wall resolutions then the xbox will scale the image to fit. Your tv may have a better scaler then the ati one in the xbox.