Knockout and MVC2: sending model to controller
===

I'm having problem with sending json from knockout to mvc2 controller action. 
Here is what I have in my View:

    var ViewModel = {
                FirstName: ko.observable("FirstName"),
                LastName: ko.observable("LastName"),
                Save: function () {
                    ko.utils.postJson(location.href, this);
                }
    }
    ko.applyBindings(ViewModel);

I have an action in controller:

    public virtual ActionResult SomeAction(MyModel model) {
            //do smth
            return View(registrationModel);
    }
    public class MyModel {
       public string FirstName {get;set;}
       public string LastName {get;set;}
    }
The problem is that i'm getting string values quoted, like "\"FirstName\"", and I know that there is some way to avoid that(work with JSON.stringify in MVC3).
I've tried the following:

    ko.utils.postJson(location.href, JSON.stringify({model: this});
also

    var json = JSON.stringify({
    FirstName: this.FirstName(),
    LastName: this.LastName()
    });
    ko.utils.postJson(location.href, JSON.stringify({model: json});
or

    ko.utils.postJson(location.href, json);
In all these 3 options I get model = null, or all the values null in Controller.

Maybe someone has done this before?
