function changeMenu()
{
	var source = $(this);
    var originalImage = source.attr("src");
    var exchangeImage = source.parent().attr("rel");
	
    source.attr("src",exchangeImage);
    source.parent().attr("rel",originalImage)
}

function setMenu(id) {
    var source = $("#" + id);
    var exchangeImage = source.parent().attr("rel");
    source.attr("src",exchangeImage);
}

$(function() {
	$("#mainNav>li>a>img").bind("mouseover", changeMenu);
	$("#mainNav>li>a>img").bind("mouseout", changeMenu);
});