[From SQL Server Magazine]
SQL Server 2008 and SQL Server 2005 include dynamic management views (DMVs) and dynamic management functions (DMFs) that provide performance-related information. However, the most useful information is obtained when you combine results from various DMVs and DMFs. For example, you can combine their results to identify T-SQL statements that are using an excessive amount of server resources.
The article continues at
http://www.sqlmag.com/Articles/Index.cfm?ArticleID=100201
