After running perfmon from Start->Run
Memory:Pages/sec
Number of pages read from disk or written to disk when Windows runs out of memory. Swapping information to and from the disk can slow down your system a lot. Consider adding more memory if you see frequency swapping.
PhysicalDisk:Avg. Disk Queue Length
How many read and write requests are waiting for the disk to respond. High numbers indicate that a faster disk drive would speed up performance.
PhysicalDisk:% Disk Time
What percentage of the time the disk was busy. This is another indicator of a slow or overloaded disk.
Processor:% Processor Time
What percentage of the time the processor was busy with all types of processes. This counter can tell you whether delays are caused by an overloaded CPU.
Originally sourced from Windows XP Cookbook, Robbie Allen & Preston Gralla
