Tips for Using SQL Server Performance Monitor Counters
Measuring Database Performance by Using Microsoft® SQL Server™ 2005
The .Net Developer And SQL Server: Working On Locks
Free Tool: SQL Sentry’s Plan Explorer
http://sqlmag.com/database-administration/free-tool-sql-sentrys-plan-explorer
http://www.sqlsentry.com/products/plan-explorer/sql-server-query-view