If you have only one multi-proc machine to generate user load on your application, you can set up the Agent and the Controller to be the same machine. Just one little tip; when assigning a test to a an agent, don’t select the “local” radio button. Picking this option will select VSTestHost.exe to run the test which in turn will use only one processor (ref: Generating heavy loads in VSTT 2008: What has changed?)
So, on the Agent Configuration screen, choose Remote and then assign “localhost” as the agent. This configuration will use QTAgent.exe and hence use multiple procs to simulate higher loads.