if (document.images) {

  nav_main_1on = new Image();
  nav_main_1on.src = "../_images/bg_side_choosing.gif";
  nav_main_2on = new Image();
  nav_main_2on.src = "../_images/bg_side_philosophy.gif"; 
  nav_main_3on = new Image();
  nav_main_3on.src = "../_images/bg_side_experience.gif";
  nav_main_4on = new Image();
  nav_main_4on.src = "../_images/bg_side_expect.gif";
  nav_main_5on = new Image();
  nav_main_5on.src = "../_images/bg_side_team.gif";
  nav_main_6on = new Image();
  nav_main_6on.src = "../_images/bg_side_opp.gif";
  nav_main_7on = new Image();
  nav_main_7on.src = "../_images/bg_side_contact.gif";

  nav_main_1off = new Image();
  nav_main_1off.src = "../_images/bg_border.gif";
  nav_main_2off = new Image();
  nav_main_2off.src = "../_images/bg_border.gif";
  nav_main_3off = new Image();
  nav_main_3off.src = "../_images/bg_border.gif";
  nav_main_4off = new Image();
  nav_main_4off.src = "../_images/bg_border.gif";
  nav_main_5off = new Image();
  nav_main_5off.src = "../_images/bg_border.gif";
  nav_main_6off = new Image();
  nav_main_6off.src = "../_images/bg_border.gif";
  nav_main_7off = new Image();
  nav_main_7off.src = "../_images/bg_border.gif";

  nav_main_4aon = new Image();
  nav_main_4aon.src = "../_images/bg_side_expect.gif";
  nav_main_4bon = new Image();
  nav_main_4bon.src = "../_images/bg_side_expect.gif";
  nav_main_4con = new Image();
  nav_main_4con.src = "../_images/bg_side_expect.gif";
  nav_main_4don = new Image();
  nav_main_4don.src = "../_images/bg_side_expect.gif";

  nav_main_4aoff = new Image();
  nav_main_4aoff.src = "../_images/bg_border.gif";
  nav_main_4boff = new Image();
  nav_main_4boff.src = "../_images/bg_border.gif";
  nav_main_4coff = new Image();
  nav_main_4coff.src = "../_images/bg_border.gif";
  nav_main_4doff = new Image();
  nav_main_4doff.src = "../_images/bg_border.gif";

}

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