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) {
		main_rd_over = newImage("images/main-rd_over.gif");
		main_or_over = newImage("images/main-or_over.gif");
		main_gn_over = newImage("images/main-gn_over.gif");
		main_bl_over = newImage("images/main-bl_over.gif");
		main_pr_over = newImage("images/main-pr_over.gif");
		main_pk_over = newImage("images/main-pk_over.gif");
		main_gr_over = newImage("images/main-gr_over.gif");
		preloadFlag = true;
	}
}