HDTV XviD or DVDRip XviD?

i have always wondered what looks better in terms of video quality; a hdtv xvid
350mb avi tv episode or a dvdrip xvid 350mb avi tv episode. i have never seen a
sample of both from the same episode to determine this. has anyone else obtained
a definitive answer?

there's no discernable difference in quality (when they're at their best) except
the dvdrips will be absent of all on screen network crap.