if (document.images)  {
    image1on = new Image();
	image1off = new Image();
	image1on.src = "images/btn_home_on.gif";
	image1off.src = "images/btn_home_off.gif";

	image2on = new Image();
	image2off = new Image();
	image2on.src = "images/btn_email_on.gif";
	image2off.src = "images/btn_email_off.gif";
} 

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