function newImage(arg) {
	if (document.images) {
		rslt = new Image();
		rslt.src = arg;
		return rslt;
	}
}

function changeImages() {
	if (document.images && (preloadFlag == true)) {
		for (var i=0; i<changeImages.arguments.length; i+=2) {
			document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
		}
	}
}

var preloadFlag = false;
function preloadImages() {
	if (document.images) {
		nav_home_over = newImage("images/nav_home-over.gif");
		nav_siding_over = newImage("images/nav_siding-over.gif");
		nav_roofing_over = newImage("images/nav_roofing-over.gif");
		nav_windows_over = newImage("images/nav_windows-over.gif");
		nav_doors_over = newImage("images/nav_doors-over.gif");
		nav_fdr_over = newImage("images/nav_fdr-over.gif");
		nav_ext_access_over = newImage("images/nav_ext_access-over.gif");
		nav_tools_over = newImage("images/nav_tools-over.gif");
		preloadFlag = true;
	}
}