What is the actual resolution of the Xvid? Most DVD players that can play MPEG4 ASP are limited to a max res of 720 x 576.
Assuming 'HD' actually means HD (720/1080p) and not 'HR' (which just means a resolution a bit higher than the normal 640 x 352), your best option is to hook your computer up to your HDTV and play it from there.
Other options are to convert to DVD - which means downscaling to SD of course - or converting to a BD5/AVCHD disc for playback on a BD player or PS3.