2 Pass Encoding with Virtual Dub

See the bottom of this URL for a quick tutorial on using virtual dub to do two pass encoding of DivX or Xvid:

http://www.shanebrinkmandavis.com/homepage/JBMM/JBMMVirtualDubTutorial.htm

And, I quote:

Below is a quick description of how to do 2-pass encoding with Virtual-Dub provided by Matthew Coulson:

In the DivX codec dialog, choose 2pass 1st pass. (Do this just before you are about to save the file).
Then, in VDub, select save as, type in any old filename, checkmark the box underneath that says "Add operation to Jobs List and defer processing", and click "Save".
Now, back in VDub, go back into the DivX codec, choose 2pass 2nd pass
Do the same thing to save it - type in the proper filename this time, checkmark the "Add to Jobs List" box again, and click "Save".
Now click on File, Job Control, and you should see the two jobs you\'ve just created
Click on Start, and VDub will go off and process the two, and you\'ll end up with the two files specified.
You can delete the first one, and keep the second. Compare it to a 1pass encode and you will notice the difference