if (document.images) {
  what_i_do = new Image();
  what_i_do.src = "http://www.sayitwithmagic.com/images/nav/what_i_do.gif";
  what_i_do_on = new Image();
  what_i_do_on.src = "http://www.sayitwithmagic.com/images/nav/what_i_do_on.gif";

  about = new Image();
  about.src = "http://www.sayitwithmagic.com/images/nav/about.gif";
  about_on = new Image();
  about_on.src = "http://www.sayitwithmagic.com/images/nav/about_on.gif";
    
  testimonials = new Image();
  testimonials.src = "http://www.sayitwithmagic.com/images/nav/testimonials.gif";
  testimonials_on = new Image();
  testimonials_on.src = "http://www.sayitwithmagic.com/images/nav/testimonials_on.gif";
  
  contact = new Image();
  contact.src = "http://www.sayitwithmagic.com/images/nav/contact.gif";
  contact_on = new Image();
  contact_on.src = "http://www.sayitwithmagic.com/images/nav/contact_on.gif";
  
  //subnav
  educational = new Image();
  educational.src = "http://www.sayitwithmagic.com/images/sub_nav/educational.gif";
  educational_on = new Image();
  educational_on.src = "http://www.sayitwithmagic.com/images/sub_nav/educational_on.gif";
  
  trade_shows = new Image();
  trade_shows.src = "http://www.sayitwithmagic.com/images/sub_nav/trade_shows.gif";
  trade_shows_on = new Image();
  trade_shows_on.src = "http://www.sayitwithmagic.com/images/sub_nav/trade_shows_on.gif";
  
  just_for_fun = new Image();
  just_for_fun.src = "http://www.sayitwithmagic.com/images/sub_nav/just_for_fun.gif";
  just_for_fun_on = new Image();
  just_for_fun_on.src = "http://www.sayitwithmagic.com/images/sub_nav/just_for_fun_on.gif";
}

function switchOn(imgName) {
    if (document.images) {
      document[imgName].src = eval(imgName + "_on.src");
    }
}
  
function switchOff(imgName) {
    if (document.images) {
      document[imgName].src = eval(imgName + ".src");
    }
}