if (document.images) {

  homeOn = new Image();
  homeOn.src = "images/buttons/home_on.gif";
  bioOn = new Image();
  bioOn.src = "images/buttons/bio_on.gif";
  scheduleOn = new Image();
  scheduleOn.src = "images/buttons/schedule_on.gif";
  retreatsOn = new Image();
  retreatsOn.src = "images/buttons/retreats_on.gif";
  workshopsOn = new Image();
  workshopsOn.src = "images/buttons/workshops_on.gif";
  aboutOn = new Image();
  aboutOn.src = "images/buttons/about_on.gif";
  teacherOn = new Image();
  teacherOn.src = "images/buttons/teacher_on.gif";
  contactOn = new Image();
  contactOn.src = "images/buttons/contact_on.gif";

  homeOff = new Image();
  homeOff.src = "images/buttons/home_off.gif";
  bioOff = new Image();
  bioOff.src = "images/buttons/bio_off.gif";
  scheduleOff = new Image();
  scheduleOff.src = "images/buttons/schedule_off.gif";
  retreatsOff = new Image();
  retreatsOff.src = "images/buttons/retreats_off.gif";
  workshopsOff = new Image();
  workshopsOff.src = "images/buttons/workshops_off.gif";
  aboutOff = new Image();
  aboutOff.src = "images/buttons/about_off.gif";
  teacherOff = new Image();
  teacherOff.src = "images/buttons/teacher_off.gif";
  contactOff = new Image();
  contactOff.src = "images/buttons/contact_off.gif";

}

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

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