If you haven’t already done so then please read the following https://tenbulls.co.uk/enlightenment/scripts/
Glenn (blog|twitter) is a well known and respected SQL Server MVP in the SQL Community and has written these fantastic scripts with versions specific to SQL 2005 and SQL 2008.
You can access his root page for the scripts from the following url SQL 2005 and 2008 Diagnostic Queries
