VSTS

Yes - you can use WatiN and Visual Studio Team System!  Simply create a brand new Unit Test within your project and use WatiN within the test methods.  The only catch is if you get an error that looks like this : 

The location of the file or directory ___ is not trusted.  To resolve this I needed to right click on BOTH WatiN.Core.dll and Interop.SHDocVw.dll and click the "Unblock" button at the bottom.  After that I needed to rebuild my project before the tests would run.

I recently encountered one of those nasty web applications that can only be created with ColdFusion by ColdFusion developers.  Yikes!  Anyways, the only real way to be able to create web tests for this particular app turned out to be the following steps:
1) Record the test steps with fiddler
2) Re-record the exact same steps with fiddler
3) Use the differences between the two recordings to determine what data to parameterize and what data to get from extraction rules.
 

In doing performance testing it is extremely common to encounter situations where your test scripts need to choose a specific link on the page based on some condition.  For example, consider the following table: