Some of the counters are averages and other counters are snapshots of values. What you need to do is apply known threshold rules for these counters. Go to

http://www.sql-server-performance.com/performance_monitor_counters_sql_server.asp

to...

Here's a spiel I've picked up from somewhere :-

In SQL Server 7.0 and later, you can access SQL Server—related performance counter values through the system table sysperfinfo in the...