function newImage(arg) {
       if (document.images) {
              rslt = new Image();
              rslt.src = arg;
              return rslt;
       }
}

function changeImages() {
       if (document.images && (preloadFlag == true)) {
              for (var i=0; i<changeImages.arguments.length; i+=2) {
                     document[changeImages.arguments[i]].src = changeImages.arguments[i+1];
              }
       }
}

var preloadFlag = false;
function preloadImages() {
       if (document.images) {
              layout_flat1_02_over = newImage("images/layout_flat1_02-over.gif");
              layout_flat1_03_over = newImage("images/layout_flat1_03-over.gif");
              layout_flat1_04_over = newImage("images/layout_flat1_04-over.gif");
              layout_flat1_05_over = newImage("images/layout_flat1_05-over.gif");
              layout_flat1_06_over = newImage("images/layout_flat1_06-over.gif");
              layout_flat1_07_over = newImage("images/layout_flat1_07-over.gif");              
              preloadFlag = true;
       }
}