var main_menu = {
	
addEvents: function() {
	
	// Load all images in the menu into an array (these will be the images in normal state)
	var normal_images = document.getElementById("menu").getElementsByTagName("img");

	for(var i = 0; i < normal_images.length; i++){
		
		normal_images[i].onmouseover = function() { this.src=this.src.replace("n_","o_"); };

		normal_images[i].onmouseout = function() { this.src=this.src.replace("o_","n_"); };
	}

}

};

main_menu.addEvents();