Counters in Performance Monitor for Collecting Usage Data for Multiple CPUs

You can also retrieve system-averaged data for multiple CPUs via Performance Monitor.
Use the System object, which includes the following counters, among others:

* % Total Processor Time
Sum of the % Processor Times for each processor divided by the number of processors in the system.

* % Total Privileged Time
Sum of the % Privileged Times for each processor divided by the number of processors in the system.

* % Total User Time
Sum of the % User Times for each processor divided by the number of processors in the system.

* % Total Interrupt Time
Sum of the % Interrupt Times for each processor divided by the number of processors in the system.

* Total Interrupts/sec
Average number of device interrupts that the processors experience per second.
This counter provides an indication of how busy system devices are on a computer-wide basis.

Source:
Microsoft SQL Server 2000 Administrator's Companion eBook