The Xbox is the first video game console to output in 'HDTV' on supporting software. It supports a variety of output resolutions, including 1280x720 (720p/D4) and 1920x1080 interlaced (1080i/D3). By default these only output at 60Hz, since the when the Xbox BIOS is set to PAL (50Hz) no HD output options are provided.
The majority of games run in progressive scan (480p/D2) only, no different to the Dreamcast, to a lesser extent the GameCube and even less the PlayStation 2. However a select few are capable of running at the higher resolutions. All images below were captured on an official development kit.
Unlike the consumer 'MS Dash' on all factory standard Xbox units, the development kit's dash will run at a variety of resolutions internally and also output in various HD formats.
Here we prove that the Xbox can run in HDTV resolutions at 50Hz (ie. for PAL regions). The PAL BIOS has the HD options removed. This mainly affects consumers in Australia since Europe has minimal to no uptake of HD, while in Aus. there's quite a few hours broadcasted on FTA everyday. The XDK is set to PAL region / 50Hz, then changed to 720p resolution.
Software running at 1080i or 720p look far superior than their SD counter-parts.