I know only one of using winrar. Right click on the file(s) to be archived and select "Add to archive...". Select "Best" in the 'compression method' listbox. If you are compressing multiple files or a folder, check the "Create solid archive" checkbox. Goto Advanced and Time tabs and clear all the checkboxes. And that's it.
DivX format is already compressed tightly enough so winrar won't be able to do much. You could try uharc compressor for such multimedia file compression.
If you ask me the best compression is using the gZip and Tar combination (Available in new version of Win Rar). First compress using Tar then with Gzip