function turnOff(imageName)   {document.getElementById(imageName).src = 'img/'+imageName + ".gif";}
function turnOn(imageName)   {document.getElementById(imageName).src = 'img/'+imageName + "-hover.gif";}

function turnOff2(imageName)   {document.getElementById(imageName).src = 'img/nav'+imageName + ".gif";}
function turnOn2(imageName)   {document.getElementById(imageName).src = 'img/nav'+imageName + "-hover.gif";}