Below are a few frames from a screencast that shows how to debug an application using the new 'Go To Reflector' functionality in TestDriven.NET 2.0. I'm using Grant Drake's NCoverExplorer as a target for the debugger. Once attached I use Reflector to view one of the loaded modules. I then set a breakpoint on the AboutDialog's OnLoad method.
The first time I open the dialog the Visual Studio 2005 debugger option Just My Code is enabled (the default). I am showing this because you will probably forget to disable this feature at least once and wonder why breakpoints are not being hit. You can find this setting under 'Options\Debugging'. Once I uncheck this setting the breakpoint is hit and I'm able to step through the x86 code. You can see me using 'Go To Reflector' on the 'Dissasembly' and 'Call Stack' windows.
You can watch the screencast here.