Till some time ago, I used to direct my customers to http://msdn.microsoft.com/en-us/sqlserver/bb671432.aspx for obtaining scripts which use the DMVs in SQL 2005/2008 to retrieve very commonly used performance troubleshooting related information. Those scripts were contributed by Microsoft’s SQL CAT team.
Unfortunately that link no longer works correctly. Luckily though the scripts are still available at different places on Script Center, and here is quick compilation of those while the original link is fixed.
SQLOS / Execution Model
List Currently-Executing Parallel Plans (the script at this link is actually the script for the next item :-))
List Cached Plans Where Worker Time Exceeds Elapsed Time (the script at this link is actually the script for the previous item :-))
I/O and Buffer cache
Locking and Blocking
Report Blocker and Waiter SQL Statements (sp_block_info)
I hope this compilation is useful to you!