function bookmark(){

	var url = "http://www.mddesignuk.com";
	var who = "MD Design UK Ltd";

	var ver = navigator.appName
	var num = parseInt(navigator.appVersion)
	if ((navigator.platform.indexOf("Win32") != -1) && (ver == "Microsoft Internet Explorer") && (num >= 4)) 
	{
   		window.external.AddFavorite(url,who);
	}
	else if (navigator.platform=="MacPPC" || navigator.platform=="Mac68K")
	{
		alert("Press Command + D together to bookmark this page.");
	}
	else
	{
   		alert("Press Ctrl + D together to bookmark this page.");
	} 
}