browser_version= parseInt(navigator.appVersion);
browser_type= navigator.appName;

if (browser_type == "Microsoft Internet Explorer" && (browser_version >= 4)) { 
document.write("<IFRAME src='calendar1.asp'	 FRAMEBORDER=0 MARGINWIDTH=0 marginheight=0 width=100% height=220></IFRAME>");
}

else  { 
document.write("<IFRAME src='calendar1.asp'	 FRAMEBORDER=0 MARGINWIDTH=0 marginheight=0 width=100% height=220></IFRAME>");

}