Move element like falling snow flake

I found a fun program that allows you to overlay snowflakes over your desktop and windows. As a programming challenge I am interested in trying to figure out how to do this myself. Not to mention that this program is a bit of a memory hog (if it doesn't have a memory leak). Below is the start I have. I am trying to get the basics down with one image and then will expand.

What I would really like help on is making the image move more smoothly and naturally.

Edit:

I posted a solution down below in the answers section but it is more CPU intensive than I would like, any thoughts?

WPF XAML code:

<Window x:Class="MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    AllowsTransparency="True"
        WindowStyle="None"
    Title="MainWindow" Height="350" Width="525" Background="Transparent" Topmost="True" WindowState="Maximized" ResizeMode="NoResize">
    <Grid Name="grid1">
        <Image Height="26" HorizontalAlignment="Left" Margin="{Binding flakeMargin}" Name="Image1" Stretch="Fill" VerticalAlignment="Top" Width="28" Source="/snowTest;component/Images/blue-pin-md.png" />
    </Grid>
</Window>

VB Code:

Imports System.ComponentModel

    Class MainWindow
        Dim bw As BackgroundWorker = New BackgroundWorker
        Dim flake0 As New flake

        Private Sub Window_Loaded(sender As System.Object, e As System.Windows.RoutedEventArgs) Handles MyBase.Loaded
            grid1.DataContext = flake0
            AddHandler bw.DoWork, AddressOf backgroundMover
            bw.RunWorkerAsync()
        End Sub

        Private Sub backgroundMover(ByVal sender As Object, ByVal e As System.