Creating performance threshold rules allows you to monitor computers for performance thresholds that you define. Microsoft Operations Manager 2000 (MOM) compares sampled values to the threshold, and when computer activity crosses the threshold, MOM generates an alert. You can define responses for threshold rules.
An example of a performance threshold is a processing rule that monitors computer processor usage, checking once every three minutes for processor usage over 75 percent. If the processor usage stays over 75 percent for an extended time, MOM can generate an alert.