var agt = navigator.userAgent.toLowerCase();
var is_major = parseInt(navigator.appVersion);
var is_minor = parseFloat(navigator.appVersion);
var is_nav = ((agt.indexOf("mozilla") != -1) && (agt.indexOf("spoofer") == -1) && (agt.indexOf("compatible") == -1) && (agt.indexOf("opera") == -1) && (agt.indexOf("webtv") == -1));
var is_nav2 = (is_nav && (is_major == 2));
var is_nav3 = (is_nav && (is_major == 3));
var is_nav4 = (is_nav && (is_major == 4));
var is_nav6 = (is_nav && (is_major == 5));
var is_gecko = (agt.indexOf("gecko") != -1);
var is_ie = ((agt.indexOf("msie") != -1) && (agt.indexOf("opera") == -1));
var is_ie3 = (is_ie && (is_major < 4));
var is_ie4 = (is_ie && (is_major == 4) && (agt.indexOf("msie 4") != -1));
var is_ie5 = (is_ie && (is_major == 4) && (agt.indexOf("msie 5.0") != -1));
var is_ie5_5 = (is_ie && (is_major == 4) && (agt.indexOf("msie 5.5") != -1));
var is_ie6 = (is_ie && (is_major == 4) && (agt.indexOf("msie 6.") != -1));
var is_ie7 = (is_ie && (is_major == 4) && (agt.indexOf("msie 7.") != -1));
var is_ff = (agt.indexOf("firefox") != -1);
var is_ff1 = (agt.indexOf("firefox/1") != -1);
var is_ff2 = (agt.indexOf("firefox/2") != -1);
var is_opera = (agt.indexOf("opera") != -1);
var is_opera2 = (agt.indexOf("opera 2") != -1 || agt.indexOf("opera/2") != -1);
var is_opera3 = (agt.indexOf("opera 3") != -1 || agt.indexOf("opera/3") != -1);
var is_opera4 = (agt.indexOf("opera 4") != -1 || agt.indexOf("opera/4") != -1);
var is_opera5 = (agt.indexOf("opera 5") != -1 || agt.indexOf("opera/5") != -1);
var is_webtv = (agt.indexOf("webtv") != -1);

function alertUserIfLessThanIE7() {
  if (is_ie4 || is_ie5 || is_ie5_5 || is_ie6)
    alert('This site is best viewed using Internet Explorer 7. Please upgrade your browser.');
}