When rendering reports, oftentimes the application would like to minimize as much of the non-report area of the viewer control as possible. This is easily accomplished when rendering the report through the built-in report viewer control hosted in the ReportServer web site (http://servername/reportserver).
Read here how to call your reports to hide the parameters: http://blogs.msdn.com/jgalla/archive/2009/03/23/hiding-parameter-area-when-viewing-reports.aspx