DivX.com offers DivX Pro for Mac and PC (Windows) for free (a $19.99 value), in the following links below.
*Catch: Requires an e-mail address to send a valid Serial Number to.(which isn't too shabby in my opinion)
Mac
http://www.divx.com/dff/index.php?version=mac
Windows (PC)
http://www.divx.com/dff/index.php?version=win
According to below posts by fellow [H] members (Thanks beowulf7), serials are all the same: A3NI9M7P47B325A52C26