system= (navigator.appVersion.indexOf("Mac")==-1)?"PC":"MAC";
browser=(navigator.appName.indexOf("Microsoft")==-1)?"NS":"IE";
BrowserOnSystem=browser+"on"+system;
switch (BrowserOnSystem) {
case "IEonPC":
document.write("");
//alert(1);
break;
case "NSonPC":
document.write("");
//alert(2);
break;
case "IEonMAC":
document.write("");
//alert(3);
break;
case "NSonMAC":
document.write("");
//alert(4);
break;
default:
document.write("");
//alert(5);
break;
}