You could use Performance Monitor (from the Reliability and Performance Monitor console).

In summary, you would have to create a task in Task Scheduler with a ‘Send an e-mail’ action, then in Performance Monitor you would create a new data collector set, and a new data collector as ‘Performance counter alert’, and add the desired counters when asked..

Then you open the properties window of the new collector and in the ‘Alert Task’ tab you add the task you previously created in Task Scheduler.

Part of this is detailed in the “Create a Data Collector Set to monitor performance counters’ section in the Performance and Reliability monitoring help.