Here is the link for XVID: (Click on the link right below "latest stable binary", the .exe file)
http://www.koepi.org/xvid.shtml
This will decode the DIVX 5 brand stuff as well, and not give that annoying DIVX LOGO. And in using this over the official DIVX5 codec, you don't get bombarded with ADWARE!
Hope this helps. (Hope I'm allowed to post links like this)
Oh yeah, this one included the encoder too!