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) {
    home_over = newImage("images/home_gs_over.jpg");
    about_over = newImage("images/about_gs_over.jpg");
    careers_over = newImage("images/careers_gs_over.jpg");
    employers_over = newImage("images/employers_gs_over.jpg");
    links_over = newImage("images/links_gs_over.jpg");
    newsltr_over = newImage("images/newsltr_gs_over.jpg");
    bookshelf_over = newImage("images/bookshelf_gs_over.jpg");
    sendemail_over = newImage("images/sendemail_over.jpg");
    home_text = newImage("images/home_text.jpg");
    about_text = newImage("images/about_text.jpg");
    careers_text = newImage("images/careers_text.jpg");
    employers_text = newImage("images/employers_text.jpg");
    links_text = newImage("images/links_text.jpg");
    newsltr_text = newImage("images/newsltr_text.jpg");
    bookshelf_text = newImage("images/bookshelf_text.jpg");   
    sendemail_text = newImage("images/sendemail_text.jpg");
    preloadFlag = true;
  }
}
preloadImages();