trouble outputting PAL footage as m2v

I had already posted this on the DVD forum, and have had no bites--but it's probably more appropriate for this new forum in any case. I'm happy to provide more specifics if anyone thinks they might have a clue.

To wit:

I have some PAL footage that I've composited some text onto using Motion. When I output to a mov file (using the animation codec), it looks fine. But, when I output it to a m2v in preparation to put it onto a DVD, the text looks all pixelated and the footage looks 'grainier'--in other words, like crap. It looks the same whether I compress it directly from Motion, or whether I compress the fine-looking mov file in compressor. I do not have this problem with any NTSC footage I've worked with. I'm actually interested in authoring the DVD as a PAL DVD w/o having to convert everything to NTSC just to get the thing done, so if anyone can think of anything I'm not taking into consideration, I'd love to know. Thanks!