Thank you to use QMC.
To keep a very good quality we use an high bitrate.
Now you can go in expert mode and take the profile for divx or xvid and play with the bitrate to diminish size of your video.
We working in easy mode with an initial bite rate of 3500k thus with a bitrate of 500k you can obtain an video size of +-450mb.
Follow this link to loo an example. : http://www.cocoonsoftware.com/index.php?option=com_content&task=view&id=113&Itemid=52
Have a nice day.