Few possible resolution to overcome the CPU utilization by scom agents.
1) Make sure that the Script scan is not enabled by default in the antivirus you are using. If it is enabled disable the same and check
2)Make sure that the \Program Files\System Center Operations Manager 2007\Health Service State is excluded from the real time scan and from schedule in case you are seeing the CPU spike at the time of schedule scan.
3)Make sure that you have the latest antivirus residing in your machine
4)Make sure that the Windows Script 5.7 is there in your system
5)Also you can check for the noisy alerts\script if any and disable those. You can make use of this blogs for the same