quads and resizing

[dig]

Hey guys,
I've been trying to use a quad in order to play an .avi file in Vizard. Somehow, the movie aspect ratio is changed. Looks ok when played in Media Player but it gets distorted (the width is compressed) when played in Vizard. (I could resize the Vizard window until the heigth/width ratio looks decend but I'd rather it looked good in full screen). What am I doing wrong here??
Cheers,
marios