I have found this query to be a very reliable indicator of CPU pressure in SQL Server 2005
-- Check SQL Server Schedulers to see if they are waiting on CPU
SELECT scheduler_id, current_tasks_count, runnable_tasks_count
FROM sys.dm_os_schedulers
WHERE scheduler_id < 255
It is much more useful in my opinion than conventional PerfMon indicators like % CPU utilization or Processor Queue Length.
