Do I absolutely have to do a full conversion or can I just modify the scale

I have a 1 hr long 320 x 240 divx avi video and want to make it a 640 x 240 divx avi video (i.e. double its width only).

I want to play it on non-highend divx avi (DVD disc) players.

Do I absolutely have to do a full conversion or can I just modify the scaling/dimension parameters (and the divx player will dimension it as it plays) ??

Thanks in advance.