screen size and accepted file formats

[musictomyears]

what size does the X5 accept for movies? not only that but why won't it play my .avi file formats? isn't that supposed to be an "acceptable" format for the X5? i am very confused.

Update: it can play the audio but not the video itself i didn't use jetaudio to convert the video. have just one final question: why doesn't the video even play in the jet audio but the .avi files play everwhere else?