http://msdn2.microsoft.com/en-us/library/ms537509.aspx
function getInternetExplorerVersion()
// Returns the version of Internet Explorer or a -1
// (indicating the use of another browser).
{
  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 = "You're not using Internet Explorer.";
  var ver = getInternetExplorerVersion();

  if ( ver > -1 )
  {
    if ( ver < 7.0 ) 
      /*msg = "You're using a recent copy of Internet Explorer."*/
	  return true;
    else
      /*msg = "You should upgrade your copy of Internet Explorer.";*/
	  return false;
  }
  //alert( msg );
}
//window.onload=checkVersion;

//http://www.javascriptkit.com/javatutors/loadjavascriptcss.shtml
function loadjscssfile(filename, filetype){
 if (filetype=="js"){ //if filename is a external JavaScript file
  var fileref=document.createElement('script')
  fileref.setAttribute("type","text/javascript")
  fileref.setAttribute("src", filename)
 }
 else if (filetype=="css"){ //if filename is an external CSS file
  var fileref=document.createElement("link")
  fileref.setAttribute("rel", "stylesheet")
  fileref.setAttribute("type", "text/css")
  fileref.setAttribute("href", filename)
 }
 if (typeof fileref!="undefined")
  document.getElementsByTagName("head")[0].appendChild(fileref)
}

//loadjscssfile("myscript.js", "js") //dynamically load and add this .js file
//loadjscssfile("javascript.php", "js") //dynamically load "javascript.php" as a JavaScript file
//loadjscssfile("mystyle.css", "css") ////dynamically load and add this .css file