How do we (while unit testing) assert if one statement was called before other

we are using RhinoMocks to unit test our wpf app.

in one of the scenarios we have a method --

public void LetsAdd()
{
    _mockableInterface1.DoSomething();
    _mockableInterface2.DoSomethingElse();
}

Now when I try to unit test LetsAdd method, I can assert if both doSomething() and DoSomethingElse() were called or not. but can I somehow also test if they were executed in this very order?

so in other words can I write a test which fails if I swap the two method calls.. ?

Thanks