var isIE6 = navigator.userAgent.toLowerCase().indexOf('msie 6') != -1;
if(isIE6)
{
   // redirection :
   window.location = "upgrade.php"; 
}

var isIE5 = navigator.userAgent.toLowerCase().indexOf('msie 5') != -1;
if(isIE5){
   // redirection :
   window.location = "upgrade.php"; 
}

  var isSafari4_1 = navigator.userAgent.toLowerCase().indexOf('4.1 safari') != -1;
if(isSafari4_1){
   // redirection :
   window.location = "upgrade.php"; 
}

  var isFF1_5 = navigator.userAgent.toLowerCase().indexOf('Firefox/1.5') != -1;
if(isFF1_5 ){
   // redirection :
   window.location = "upgrade.php"; 
}

	var isFF2_0 = navigator.userAgent.toLowerCase().indexOf('Firefox/2.0') != -1;
if(isFF2_0 ){
   // redirection :
   window.location = "upgrade.php"; 
}

//var isIE7 = navigator.userAgent.toLowerCase().indexOf('msie 7') != -1;
//if(isIE7){
   // redirection :
//  window.location = "accueil.php"; 
//}