if(document.images){
   var imgOut = new Object();
   imgOut["logo"] = new Image(310, 130);
   imgOut["logo"].src = "/images/logo.jpg";

   var imgOver = new Object();
   imgOver["logo"] = new Image(310, 130);
   imgOver["logo"].src = "/images/logo-lite.jpg";
}


function swapImage(evt){
   if(document.images){
      evt = (evt) ? evt : ((window.event) ? window.event : null);
      if(evt){
         var elem = (evt.target) ? evt.target : ((evt.srcElement) ? evt.srcElement : null);
         if(elem && elem.className == "swappable"){
            switch (evt.type){
               case "mouseover":
                  elem.src = imgOver[elem.id].src;
                  break;
               case "mouseout":
                  elem.src = imgOut[elem.id].src;
                  break;
            }
         }
      }
   }
}
document.onmouseover = swapImage;
document.onmouseout = swapImage;