Indexed Views vs. Regular Views
SQL Server 2005 and SQL Server 2000 support indexed views, which are also known as materialized views. When a unique clustered index is added to a view, the resulting indexed view materializes and persists the data in physical storage. Unlike regular views, which are virtual and take up only temporary storage space at runtime, indexed views are permanent and require permanent disk storage. You can read more about indexed views in the SQL Server 2005 Books Online (BOL) documentation at www.microsoft.com/technet/prodtechnol/sql/2005/impprfiv.mspx.