If you're well-versed in using PerfMon, I'd like to hear about the counters that you use regularly and what constitutes a good or bad value.
However, it's a rare individual who knows their way around PerfMon and its multitude of performance objects and counters. Which ones should you track? And even if you know the right ones to track, what values indicate good or bad performance?
If you've ever struggled with knowing which PerfMon counters to track for SQL Server performance, take a look at my TechTarget series of screencasts at SearchSQLServer.com. They'll give you most everything you need to know about using PerfMon and assessing PerfMon counters to learn about the behavior of SQL Server. It's a four-part series with the first two sessions, PerfMon Counters for Tracking Memory and PerfMon Counters for the Windows OS, already posted. These screencasts not only tell you which counters to track and why, but also what are the general rules of thumb for good performance when using these counters.
P.S. I cover a variety of PerfMon counters in these screencasts. Many of them are discussed in an excellent document put together by Microsoft PSS. Read their blog at http://blogs.msdn.com/psssql/default.aspx.