var imgsNameArray = new Array('nav_home','nav_services','nav_clients','nav_about','nav_contact');
var imgDir = '../images/header/';

if (document.images) {    
	for (var i = 0; i < imgsNameArray.length; i++) {
	imgName = imgsNameArray[i];
	img_on[imgName]= new Image();
	img_on[imgName].src = imgDir + imgName + '_on2.gif';
	img_off[imgName]= new Image();
	img_off[imgName].src = imgDir + imgName + '_off2.gif';
	}
}

// Set Image to "On" State
function img_on(imgName) {
	if (document.images) {
		document[imgName].src = img_on[imgName].src;
	}
}

// Set image to "Off" State
function img_off(imgName) {
	if (document.images) {
		document[imgName].src = img_off[imgName].src;
	}
}