if (document.images) {
    // preload the alternate images offscreen
   homeon = new Image();
   homeon.src = "images/disc.gif";
   contacton = new Image();
   contacton.src = "images/disc.gif";
   weddingon = new Image();
   weddingon.src = "images/disc.gif";
   homeoff = new Image();
   homeoff.src = "images/cd1.gif";
   contactoff = new Image();
   contactoff.src = "images/cd1.gif";
   weddingoff = new Image();
   weddingoff.src = "images/cd1.gif";
}

function imgAct(imgName) {
  if (document.images) {
     document[imgName].src = eval(imgName + "on.src");
 }
}

function imgInact(imgName) {
  if (document.images) {
     document[imgName].src = eval(imgName + "off.src");
 }
}