Scare A Fellow Windows XP User

View the image in full. It's a .gif image that can freak out the average Windows XP user. Just simply download this and put it on the user's Windows XP computer. Then open the picture and put it into full screen. Pause it (upper right hand corner) and move the mouse to the bottom. The rectangle thing will go away and it will look like their screen saver. I've tricked people with this and freaked them out.
Must be Windows XP for best results, obviously. Simple enough?