var aryImages = new Array('images/about-us-button.gif', 'images/about-us-button-over.gif','images/services-button.gif', 'images/services-button-over.gif','images/driver-spotlight-button.gif', 'images/driver-spotlight-button-over.gif','images/contact-us-button.gif', 'images/contact-us-button-over.gif');

for (i=0; i<aryImages.length; i++)
{
	var preload = new Image();
    preload.src = aryImages[i];
}

function swapImage(img, imgIndex)
{
	document[img].src = aryImages[imgIndex];
}