I think there is a lot to do with the drive u're using if u play the movie from a iso9660 CD.
I'm using a samsung drive.
I compared it to my friend's RCA one and there is a difference.
I'm using the latest CVS build of XBMP. I watch a divx or xvid movie almost every other day and has never encountered any "skipping" or "Choppy" play. I loads for about 8 seconds, and then plays till the end smoothly.
To get even better performance, copy the whole movie to the HD.
BTW, i dont know why but caching somehow stopped working for me.
I turn on the cache function but it will still directly play.
But who cares, it would still play smoothly ^^
I do wish that XBMP will add a new function to enable us to copy iso9660 material to the XBOX HD.
Since it's like the only program out there that supports iso9660. (correct me if i'm wrong)