// 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(180,45);
oneoff = new Image(180,45);

oneon.src = "images/nav/contact_on.gif";
oneoff.src = "images/nav/contact_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');
}
// -->