Database diagram support objects cannot be installed (SQL Server 2005/2008)

Solution for the following error in SQL Server 2005 or 2008

Database diagram support objects cannot be installed because this database does not have a valid owner. To continue, first use the Files page of the Database Properties dialog box or the ALTER AUTHORIZATION statement to set the database owner to a valid login, then add the database diagram support objects." 

iisapp Tool on windows server 2008

Following commmand is the alternative for IISAPP in windows 2008 server

%windir%\system32\inetsrv\appcmd.exe list WP