ratio of 768x576? Here's what I do.
I get scenes from DVDs with DVD Shrink and then convert to AVI with AutoGK.
I then make my own music videos with Windows Movie Maker.
I then publish them to the computer ready to burn with DVD Flick.
If I publish using the "Best quality for playback on my computer" setting, then it works fine and I get a ratio of 768x576.
But if I do the same useing "DVD quality (3Mbps)" setting then the ratio comes out as 720x576 instead of 768x576. This means the picture is better quality once burnt to disc, but the incorrect ratio means everyone looks too tall.

I have tried resizing it back to 768x576 with Windows Media Encoder 9. It works a treat, but than the audio becomes corrupted (crackly).
As I much prefer the DVD quality (indeed, it's almost as good as the master copies I shrink) I am hoping that you clever chaps and chapesses can help?