Java Script Pre loading images

Hi all,

I put a bit of java script in my page that makes an image change when the text right beside it is hovered over. However, the images are being called each time instead of being preloaded. Is there a way to preload the images so that the hover transitions are smoother (similar to the way it is done using css)

site is:
The part I am talking about is under AirCell working diagram, midway down the page.


I think I figured it out.
Can anyone comment if this is correct?

That should do it.