The next step in our setup is to stress test the web farm/sql cluster. I considered Application Center Test (ACT) that is included in Visual Studio Enterprise, as well as the Web Application Stress tool (WebTool) (WAS Tutorial).

ACT is integrated with Visual Studio .Net. It also has a command-line interface, so you can schedule tests for unattended operation. However, the version bundled with .Net does not allow the test to have multiple client machines. (I couldn't find any other version, however. I assume there is a version included in Application Center 2000, but that's a big load balancing solution that I didn't want to investigate.)

WebTool is an older product, but is still usable. The key part, for me, is that it installs a service on the machine. Each machine that has the service installed can be controlled by any other machine with WebTool installed. In our load-balanced web farm, I need to simulate traffic from different IP ranges. This distributed testing model will do that quite nicely