Web Service Load Testing Tools...

In the past, I've used Microsoft Web Application Stress Tool - I think they called it Homer before.  Now, I'm using ACT (Application Center Test) to perform load/response testing for my web services.  Looking at the app, it seems like I have less options available to me (although really cool results gathering and display options) for the execution of the tests.  For example, I couldn't find a way to throttle the tests through the GUI.

I decided to crack open the xml file that defines the test used by ACT.  Looks like there are a lot more settings I can play with.  I can't seem to find any good documentation for this however.  Looks like I can play with throttling after all...... I guess I'll just have to play around until I figure it out.  Any help would be nice...  If these are configurable settings, I wonder why they aren't configurable through the GUI - or even documented in the help...

Here's an example of a test file....

<DefaultValues>