Download an updated version of Books Online for Microsoft SQL Server 2005. Books Online is the primary documentation for SQL Server 2005. The September 2007 update to Books Online contains new material and fixes to documentation problems reported by customers after SQL Server 2005 was released. Refer to “New and Updated Books Online Topics” for a list of topics that are new or updated in this version. Topics with significant updates have a Change History table at the bottom of the topic that summarizes the changes. Beginning with the February 2007 update, SQL Server 2005 Books Online reflects product upgrades included in SQL Server 2005 Service Pack 2 (SP2).
Reference : Pinal Dave (http://blog.SQLAuthority.com)