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) {
		home_over = newImage("images/home-over.gif");
		home_down = newImage("images/home-down.gif");
		aboutus_over = newImage("images/aboutus-over.gif");
		aboutus_down = newImage("images/aboutus-down.gif");
		courses_over = newImage("images/courses-over.gif");
		courses_down = newImage("images/courses-down.gif");
		career_over = newImage("images/career-over.gif");
		career_down = newImage("images/career-down.gif");
		resources_over = newImage("images/resources-over.gif");
		resources_down = newImage("images/resources-down.gif");
		calendar_over = newImage("images/calendar-over.gif");
		calendar_down = newImage("images/calendar-down.gif");
		help_over = newImage("images/help-over.gif");
		help_down = newImage("images/help-down.gif");
		contactus_over = newImage("images/contactus-over.gif");
		contactus_down = newImage("images/contactus-down.gif");
		register_over = newImage("images/register-over.gif");
		register_down = newImage("images/register-down.gif");
		mycourses_over = newImage("images/mycourses-over.gif");
		mycourses_down = newImage("images/mycourses-down.gif");
		instructorprofiles_over = newImage("images/instructorprofiles-over.gif");
		instructorprofiles_down = newImage("images/instructorprofiles-down.gif");
		preloadFlag = true;
	}
}