Does anybody out here have any tweaking recommendations for the Divx 5.xx Pro codec?

I have a 161min Huffy-AVI that I am trying to convert to a cd-size divx file (~485kbps). When I run it thru the divx 3.xx codec in Vdub the file works fine. However when I use any form of Divx 5.xx (think I had similar problems with 4.xx too) the blockiness is *very* bad and the movie quality is unacceptable.

I have looked for a little info on the main divx site, but as of yet have not found any good tweaking ideas.

4.xx/5.xx have all of these supposed wonderful new tweaking paramenters that I would love to learn how to use.

The original works great, just has next to *nothing* in the way of tweaking options.

Your opinions are appreciated.

-elf