Download free SQL Server 2008 System Views Map

Microsoft also offers some free goodies sometime and here is one...

If you want a good diagram shows the key system views and relationship between then please visit at http://www.microsoft.com/downloads/en/details.aspx?FamilyID=531c53e7-8a2a-4375-8f2f-5d799aa67b5c&displaylang=en.