A good idea Dave, but this wouldn't work for my scenario (i wasn't clear enough in my original post)

The rollover changes an image below the navigation menu so when i switch skins from a vertical layout to a horizontal menu layout i dont want the image to be displayed at all. I can set this to a 1px x 1px clear image, but when i rollover the nav buttons the JavaScript still stands - therefore i need to put somekind of If statement into tthe javascript to say determine which image is displayed within the image