480 is the best option, since your source material is 480. Uprezzing to 720 will give lousy results, because you are working with heavily compressed (and copyrighted) material. Better get the source material from the copyright owner.
thanks for that I'll use 480 - then I assume that all vob files are 480 then??
As to getting the source material it's from a Chinese company and English is a bit of an issue
thanks for the info
You could try Mandarin.
Or maybe Cantonese?
Seriously, sometimes it is possible to get a good image out of a DVD. It depends on the original quality, the amount of movement, various things.
Standard Definition files are generally 640X480 (Square Pixels). If you export that way you should be safe. However, if someone tries to play it back full screen on a PC it might not look very good. On the other hand, most DVD players do a pretty darn good job of scaling it up to play on an HDTV.