function SimpleSwap(el,which){
          el.src=el.getAttribute(which || "origsrc");
        }

        function SimpleSwapSetup(){
          var x = document.getElementsByTagName("img");
          for (var i=0;i<x.length;i++){
            var oversrc = x[i].getAttribute("oversrc");
            if (!oversrc) continue;
              
            // preload image
            // comment the next two lines to disable image pre-loading
            x[i].oversrc_img = new Image();
            x[i].oversrc_img.src=oversrc;
            // set event handlers
            x[i].onmouseover = new Function("SimpleSwap(this,'oversrc');");
            x[i].onmouseout = new Function("SimpleSwap(this);");
            // save original src
            x[i].setAttribute("origsrc",x[i].src);
          }
        }

        var PreSimpleSwapOnload =(window.onload)? window.onload : function(){};
        window.onload = function(){PreSimpleSwapOnload(); SimpleSwapSetup();}