Microsoft Windows Media Video 9 VCM (Video Compression Manager), based version of the Windows Media Video 9 encoder/decoder, will enable legacy encoding and editing applications to support the Windows Media Video 9 codec in file containers such as AVI. The codecs offer the best experience when delivered using the ASF file container.

Once installed, legacy solutions will automatically be able to use the codec via the VCM interface. The VCM includes a property page so that users can set encoding parameters.
More info:
hxxp://www.microsoft.com/windows/windowsmedia/9series/codecs/video.aspx
Download:
hxxp://download.microsoft.com/download/9/8/a/98a6cb2d-6659-485e-b1f9-2c0d9bf6c328/wmv9VCMsetup.exe