function getInternetExplorerVersion()
// Returns the version of Internet Explorer or a -1
// (indicating the use of another browser).
{
  var rv; // 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;
}

var browser=navigator.appName;
var version=getInternetExplorerVersion();

if (browser == "Microsoft Internet Explorer" && version < 7) {
  document.write("<p style=\"text-align: left; width: 80%; margin: 0 auto; color: red;\">We see that you are using a version of "+ browser + " " + version + " that is not compatible with our website. <strong>If you continue you will experience problems</strong>. Please upgrade to <a href=\"http://www.ie8optimized.com/IE8/?pkw=internet_explorer_update\">" + browser + " version 7 or higher</a> or use a different browser like <a href=\"http://www.firefox.com\">Mozilla's Firefox</a>, <a href=\"http://www.google.com/chrome\">Google's Chrome</a>, or <a href=\"http://www.apple.com/safari/download\">Apple's Safari</a> for a better, faster, and safer internet experience.</p>");
}