var browser_type=navigator.appName
var browser_version=parseInt(navigator.appVersion)
//if NS 6
if (browser_type=="Netscape"&&browser_version>=5)
window.location.replace("main_index.htm")
//if IE 4+
else if (browser_type=="Microsoft Internet Explorer"&&browser_version>=4)
window.location.replace("main_index.htm")
//if NS4+
else if (browser_type=="Netscape"&&browser_version>=4)
window.location.replace("main_index.htm")
//Default goto page (NOT NS 4+ and NOT IE 4+)
else
window.location="main_index.htm"