If you want to dig deeper into the load testing features found in Team System, you should read this new article (Monitoring and Analyzing a Load Test Result) by Rick Potts, a developer on the load testing team.
Summary: Microsoft Visual Studio Team Test Edition provides tools for running, monitoring, and analyzing load tests. The load test result viewer is capable of monitoring a running test or analyzing a completed test. This document describes the features of the load test result viewer. (23 printed pages)