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) {
		but_home_over = newImage("images/but-home-over.gif");
		but_about_over = newImage("images/but-about-over.gif");
		but_exposure_over = newImage("images/but-exposure-over.gif");
		but_Overview_over = newImage("images/but-Overview-over.gif");
		but_Veneers_over = newImage("images/but-Veneers-over.gif");
		but_Crowns_over = newImage("images/but-Crowns-over.gif");
		but_Whitening_over = newImage("images/but-Whitening-over.gif");
		but_mercury_over = newImage("images/but-mercury-over.gif");
		but_preventive_over = newImage("images/but-preventive-over.gif");
		but_practice_over = newImage("images/but-practice-over.gif");
		but_doctor_over = newImage("images/but-doctor-over.gif");
		preloadFlag = true;
	}
}