if (document.images)
	{
	// preload navigation button images
	nzSt = newImage("images/home/new_zealand.gif");
	nzOv = newImage("images/home/new_zealand_ov.gif");
	auSt = newImage("images/home/australia.gif");
	auOv = newImage("images/home/australia_ov.gif");
	otSt = newImage("images/home/distance.gif");
	otOv = newImage("images/home/distance_ov.gif");
	preloadFlag = true;
	}