What is best dimensions for capturing analog video from old vid ta

I did some checking online, and thought I found something that stated that
720x480 was a good dimension size for video, especially if you want to create
DVD's with the files later. But after doing a couple, I think it looks like
my images are a little stretched out of proportion as opposed to 640x480! Is
there a difference, or is it my imagination? These are old vids of my son
when he was a boy, and I want to preserve them in the best way I can so he
can pass them on to his family. I am doing as I was advised here and saving
as .avi after capturing, but now not sure about size. Please advise. Thanks
in advance.