Hyper-threading (HT) is the brand name for the technology Intel uses in many of its Xeon 32-bit processors that enables one physical processor core to execute two instruction streams (or threads) concurrently. On an HT machine, when HT is enabled, each physical processor currently presents two “logical” CPU interfaces to the operating system so that [...]

Look at a combination of processor utilization and processor queuing.
(1) The primary indicator of processor utilization is the % Processor Time Counter in the Processor Object. Note that the _Total instance of the Processor Object is actually the average value over all processors. The System Object in NT 4.0 contains a Counter named % Total [...]