MainWindow - Replaced Window property with Page property so app can be a navigation app. NavigationWindow uses this page as it's source.

MainWindow.cs

using System.Windows.Navigation;

namespace RegistrationKiosk
{
	/// <summary>
	/// Interaction logic for MainWindow.xaml
	/// </summary>
	public partial class MainWindow : Page
	{
		public MainWindow()
		{
			InitializeComponent();
		}

		
		private void MainWindow_OnMouseDown(object sender, MouseButtonEventArgs e)
		{
			NavigationService nav = NavigationService.GetNavigationService(this);
			nav.Navigate(new Uri("CardSwipe.xaml", UriKind.RelativeOrAbsolute));
		}
	}


}

<Page x:Class="RegistrationKiosk.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Height="{Binding SystemParameters.PrimaryScreenHeight }" 
        Width="{Binding SystemParameters.PrimaryScreenWidth}" 
        MouseDown="MainWindow_OnMouseDown"
        >

        <Grid Name="MainWindowFrame">
        <Grid.Background>
            <ImageBrush ImageSource="Images/attract.gif" >

            </ImageBrush>
        </Grid.Background>
    </Grid>