Binding to a ViewModel property

Please bear with me, I know very little about WPF so I might be way off target with this...

I currently have a static resource defined as follows:

<XmlDataProvider 
    x:Key="staticData" 
    Source="http://someurl/desktopservices/some.xml" 
    XPath="/menu"/>

This is bound to a Menu control as follows:

<Menu 
    ItemsSource="{Binding Source={StaticResource staticData}}" 
    x:Name="MyMenu" />

All is good.

Now I define a view model and create the XmlDataProvider as a propery of the vm:

public class ViewModel : INotifyPropertyChanged
{
    private readonly XmlDataProvider dataProvider;

    public ViewModel()
    {
        var document = new XmlDocument();
        document.Loa开发者_运维百科d("http://someurl/desktopservices/some.xml");
        dataProvider = new XmlDataProvider
                           {
                               Document = document,
                               XPath = @"/menu"
                           };
    }

    public XmlDataProvider DataProvider
    {
        get
        {
            return dataProvider;
        }
    }

    //....
}

The ViewModel is then defined in XAML as another StaticResource:

<local:ViewModel x:Key="vm"/>

How do I change my binding to the DataProvider property of the view model? I would expect:

<Menu 
    ItemsSource="{Binding DataProvider, Source={StaticResource vm}}" 
    x:Name="MyMenu" />

(I've tried other combos... this is the one that doesn't error... however nothing gets bound)