I have notifications working now, at least for "down" events. Is there a way I can set a notification on CPU utilization above some threshold using Cisco System Health SNMP sensor, without having to set that notification on each of those sensors individually?
You can use the sensor channel settings to set error and warning limits for a certain channel. This can be done for multiple sensors using multi-edit. To apply a notification to several sensors you might create a library an then add the notification to the library itself as every included sensor will use the same.
In the library overview you should see a tab called Notifications. There you can add the different triggers. Please not that this feature was only introduced in late PRTG 12 so if you are on a lower version a update might be required to use this feature.
Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.