// check if the browser is Navigator 3 or higher:
agent = navigator.userAgent;
browserVer = 2;
if (agent.substring(0,7) == "Mozilla")
{
    if (parseInt(agent.substring(8,9)) >= 3) {
          browserVer = 1;
     }
}

// preload universal images:

if(browserVer == 1){

oneon = new Image(120,30);
oneoff = new Image(120,30);

twoon = new Image(120,30);
twooff = new Image(120,30);

threeon = new Image(120,30);
threeoff = new Image(120,30);

fouron = new Image(120,30);
fouroff = new Image(120,30);

fiveon = new Image(120,30);
fiveoff = new Image(120,30);

sixon = new Image(120,30);
sixoff = new Image(120,30);

oneon.src = "../images/nav/about_on.gif";
oneoff.src = "../images/nav/about_off.gif";

twoon.src = "../images/nav/treatments_on.gif";
twooff.src = "../images/nav/treatments_off.gif";

threeon.src = "../images/nav/resources_on.gif";
threeoff.src = "../images/nav/resources_off.gif";

fouron.src = "../images/nav/contact_on.gif";
fouroff.src = "../images/nav/contact_off.gif";

fiveon.src = "../images/nav/subscribe_on.gif";
fiveoff.src = "../images/nav/subscribe_off.gif";

sixon.src = "../images/nav/contact2_on.gif";
sixoff.src = "../images/nav/contact2_off.gif";

}
function press(imgName) {
    if (document.images)
      document[imgName].src = eval(imgName + 'on.src');
}
function release(imgName) {
  if (document.images)
    document[imgName].src = eval(imgName + 'off.src');
}
// -->