i make dvd rips of movies to divx with DVDx and they look very good....but they could look better.....i have heared that a 2-Pass CBR will deliver better results....how will it be better??? is it because it knows where to use bits better?

well what i want to know is how i can do it in dvdx.....and is it worth it??? at the moment i can convert a 90min movie in less than 2 hours when i encode it to divx 5.0.4.....if i do a 2 pass it will take twice as long....am i correct???? any help will be apreciated...