var check_browser = "nn6"; 
var macos = false;
if(document.getElementById) check_browser = "nn6";
if(document.all) check_browser = "ie";
//if(document.layers) check_browser = "nn";
if(document.layers) check_browser = "nn6";
if(navigator.userAgent.toLowerCase().indexOf("mac")) macos = true;
if(navigator.userAgent.toLowerCase().indexOf("ppc")) macos = true;
if(navigator.userAgent.toLowerCase().indexOf("powerpc")) macos = true;
document.write("<script language=\"JavaScript1.2\" src=\"preview_"+check_browser+".js\"></script>");