AFAIK, XviD asd is just a name for the Polish ripping group, not a new codec. Sync problems are usually caused by VBR audio. Why people do that is beyond me, the space saved by making the audio variable bitrate is negligible.
My recommendatios:
1) Don't fool with AVIs with VBR, some cannot be fixed, others can but will cause you a lot of grief.
2) Try AviDemux, it handles VBR audio about as well as anything:
http://www.videohelp.com/tools/AviDemux
3) Try one of the all-in-one converters on this page if AviDemux doesn't work:
http://www.videohelp.com/tools/secti...dvd-converters
4) Don't use Nero for anything besides burning.
5) There are more advanced methods if one is really determined, but again, it's not worth the effort.
Good luck.
