Windows Live Essentials, which refers to the suite of Windows Live client applications (as opposed to web services), consists of a long list of software: Messenger, Mail, Photo Gallery, Movie Maker, Writer, Toolbar, Family Safety, Office Live Add-in, and Silverlight. Movie Maker beta is the only application that is not checked by default, likely due to the fact that the team couldn't finalize it in time for the release.
Full Story: http://arstechnica.com/journals/microsoft.ars/2009/01/08/windows-live-essentials-including-messenger-wave-3-final
