If you change the resolution it will change the size of the file and vice versa. But these also depend on the length of the flick. I typically use a file size of 400 =/-50mb for a 2 hour movie. This is pretty good for most movies. In my past readings here, most people are around that range.
Take a look at this thread. Some comments there too.
http://www.aximsite.com/boards/showt...highlight=fair