Taking a screenshot using XNA 4.0 and C#

I've been working a lot on an old game that a few friends and I made in college. We ported it to C# using the XNA framework and it's working great! You can read more about that project by clicking here.

The old code was C++ with OpenGL. One of the functions I had a hard time porting was taking a screenshot. Older versions of XNA seemed to have a way to do it, but the newest version, 4.0, didn't have an easy way to do it. Here's what I ended up doing:
public void ScreenShot(string prefix) {
    #if WINDOWS
    int w = GraphicsDevice.PresentationParameters.BackBufferWidth;
    int h = GraphicsDevice.PresentationParameters.BackBufferHeight;

    //force a frame to be drawn (otherwise back buffer is empty)
    Draw(new GameTime());

    //pull the picture from the buffer
    int[] backBuffer = new int[w * h];
    GraphicsDevice.GetBackBufferData(backBuffer);

    //copy into a texture
    Texture2D texture = new Texture2D(GraphicsDevice, w, h, false, GraphicsDevice.PresentationParameters.BackBufferFormat);
    texture.SetData(backBuffer);

    //save to disk
    Stream stream = File.OpenWrite(prefix + "_" + Guid.NewGuid().ToString() + ".png");
    texture.SaveAsPng(stream, w, h);
    stream.Close();

    #elif XBOX
    throw new NotSupportedException();
    #endif
}
Here's an article you can check out that explains the new behavior:
http://blogs.msdn.com/b/shawnhar/archive/2010/03/30/resolvebackbuffer-and-resolvetexture2d-in-xna-game-studio-4-0.aspx