The codec packs contains a Settings Application to use in conjunction with your windows media center setup which will enable each user to choose from different splitters and decoders for specific filetypes.The application will also allow you to choose from 10 different  speaker configurations form 'same as input' and all the way up to full 7.1 channel output.                                                        The Settings Application is 100% UAC compliant.
The Application allows each user to maintain individual codec settings while at the same time seamlessly integrating any administrative commands directly into the users account. New users accounts are detected upon opening the Application and automatically inherit the Administrators settings.
Adding files to the Windows Media Player Playlist.                                       
On the Help TAB of the 32bit Settings Application is a button to allow you to choose Windows Media Player Filetype Associations. Once you have used this button, you can Enqueue newly associated files to the Windows Media Player Playlist as depicted below. If for some reason this doesn't work for you, go back to the associations button, click No twice, consecutively, then select Yes. No reboot is required.