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

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

var preloadFlag = false;
function preloadImages() {
	if (document.images) {
		var nav_01_a = newImage("nav/a/nav_01.png");
		var nav_02_a = newImage("nav/a/nav_02.png");
		var nav_03_a = newImage("nav/a/nav_03.png");
		var nav_04_a = newImage("nav/a/nav_04.png");
		var nav_05_a = newImage("nav/a/nav_05.png");
		var nav_06_a = newImage("nav/a/nav_06.png");
		var nav_07_a = newImage("nav/a/nav_07.png");
		var nav_08_a = newImage("nav/a/nav_08.png");
		//
		preloadFlag = true;
	}
}