function checkVersion(){
   if(isOldBrowser()){
   }
   else{
      setStyleSheetEnabled('modern', true);
      setStyleSheetEnabled('standard', false);
   }
}

function isOldBrowser(){

   var nVer = navigator.appVersion;
   var nAgt = navigator.userAgent;
   var browserName  = '';
   var fullVersion  = 0; 
   var majorVersion = 0;

   // In Internet Explorer, the true version is after "MSIE" in userAgent
   if ((verOffset=nAgt.indexOf("MSIE"))!=-1) {
      browserName  = "Microsoft Internet Explorer";
      fullVersion  = parseFloat(nAgt.substring(verOffset+5));
      majorVersion = parseInt(''+fullVersion);
   }

   // In Opera, the true version is after "Opera" 
   else if ((verOffset=nAgt.indexOf("Opera"))!=-1) {
      browserName  = "Opera";
      fullVersion  = parseFloat(nAgt.substring(verOffset+6));
      majorVersion = parseInt(''+fullVersion);
   }

   // In most other browsers, "name/version" is at the end of userAgent 
   else if ( (nameOffset=nAgt.lastIndexOf(' ')+1) < (verOffset=nAgt.lastIndexOf('/')) ) 
   {
      browserName  = nAgt.substring(nameOffset,verOffset);
      fullVersion  = parseFloat(nAgt.substring(verOffset+1));
      if (!isNaN(fullVersion)) majorVersion = parseInt(''+fullVersion);
      else {fullVersion  = 0; majorVersion = 0;}
   }

   // Finally, if no name and/or no version detected from userAgent...
   if (browserName.toLowerCase() == browserName.toUpperCase()
      || fullVersion==0 || majorVersion == 0 )
   {
      browserName  = navigator.appName;
      fullVersion  = parseFloat(nVer);
      majorVersion = parseInt(nVer);
   }
   if(browserName == "Microsoft Internet Explorer" && majorVersion >= 7) return false;
   else if(browserName == "Opera" && majorVersion >= 9) return false;
   else if(browserName == "Firefox" && majorVersion >= 2) return false;
   else return true;

}

function setStyleSheetEnabled(title, enabled) {
   var i, a;
   var links = document.getElementsByTagName("link");
   for(i=0; (a = links[i]); i++) {
      if(a.getAttribute("rel").indexOf("style") != -1 && a.getAttribute("title") == title) {
         a.disabled = !enabled;
         //alert(title+=enabled);
      }
   }
}