Best settings for video?

Hi

Could anybody steer me in the right direction with regards the best conversion settings for video please?
I've spent a week os so trawlling round various sites but without a definitive answer.
If I want to convert dvds to play on the phone, what are the best settings? mp4? wmv? avi? resolution? 800x480 is an odd size, so stick at 640 x 480? Frame rate? 25, 30? etc.
Just want them to look good, sound good and play without being jaggy or jerky.

Appreciate any help.

Thanks

Mike