Ejemplo event ws WP7

   Private Sub btnIngresar_Click(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles btnIngresar.Click
        'Dim usu As String = txtusu.Text
        'Dim cla As String = txtcla.Password
        'If usu = "luis" And cla = "123" Then
        '    NavigationService.Navigate(New Uri("/Perfil.xaml?user=" & usu, UriKind.Relative))
        'Else
        '    MessageBox.Show("Error al Ingresar", "Error", MessageBoxButton.OK)
        'End If

        Dim servicio As New Service1SoapClient()
        servicio.validarUsuarioAsync("", "")
        AddHandler servicio.validarUsuarioCompleted, AddressOf Me.validar_usuarioCompleted
    End Sub

    Sub validar_usuarioCompleted(ByVal sender As Object, ByVal e As validarUsuarioCompletedEventArgs)
        Dim resultado As String = e.Result
    End Sub