Check IE by Javascript

    function getInternetExplorerVersion()

    {

        var rv = -1; // Return value assumes failure.

        if (navigator.appName == 'Microsoft Internet Explorer')

        {

            var ua = navigator.userAgent;

            var re = new RegExp("MSIE ([0-9]{1,}[\.0-9]{0,})");

            if (re.exec(ua) != null)

                rv = parseFloat(RegExp.$1);

        }

        return rv;

}

    function checkVersion()

    {

var msg = "The site is best viewed with Internet Explorer Version 6 and above.\n\nThe page might not be properly displayed if viewed on your current browser.";

      

var ver = getInternetExplorerVersion();

        if (ver > -1)

        {

            if (ver >= 6.0)

                msg = ""

        }

        if(msg != "")

        {

            alert(msg);

        }

}