If you have installed Windows Media Services Administrator for the Web or are hosting Web sites to distribute your content, you should consider using Web server permissions. Permissions set on your Internet Information Services (IIS) Web server apply to all users accessing your Web sites; whereas, NTFS file system permissions apply only to a specific user or group of users with a valid Windows-based account. IIS permissions enable you to control access to virtual directories on your Web site in the same manner that the NTFS file system permissions control access to folders on your server.
When users access your Web site by using anonymous authentication, they use the IUSR_computername account. By default, they receive NTFS file system permissions for the folders and files on your Web site, which you can change by using Web server permissions.
For more information about Web server permissions, see IIS Help.