drop down menu - that loads page in the same page! - JavaScript and CSS

Hi,

I´m trying to create a drop down menu that loads a page when a option is selected.
same as the php function "include("path")".

The code below works only for firefox :confused: not for IE, safari, chrome
Please help me out. I have tried to create this simple function for hours.


<script type="text/javascript">

function loadXMLDoc(url)

{

if (window.XMLHttpRequest)

  {// code for IE7+, Firefox, Chrome, Opera, Safari

  xmlhttp=new XMLHttpRequest();

  }

else

  {// code for IE6, IE5

  xmlhttp=new ActiveXObject("Microsoft.XMLHTTP");

  }

xmlhttp.open("GET",url,false);

xmlhttp.send(null);

document.getElementById('priser').innerHTML=xmlhttp.responseText;

}

</script>


</head>


<body>

<h1><span class="redProdHeader"> Beställning av 

affischer </span>  </h1>

<form action="../tryckeri/form/offertTryckeriMail.php" method="post" name="offertTryckeri" id="offertTryckeri" enctype="multipart/form-data">


  <p><strong>Format:</strong><br />

    <select name="button" >

      <option>--- Välj Format ---</option>

      <option value="b2" ></option>

      <option value="a0" onclick="loadXMLDoc('../tryckeri/affischer/priser/A0Priser.php')">A0</option> 

      <option value="a1" onclick="loadXMLDoc('../tryckeri/affischer/priser/A1Priser.php')">A1</option>

      <option value="a2" onclick="loadXMLDoc('../tryckeri/affischer/priser/A2Priser.php')">A2</option>

      <option value="a3" onclick="loadXMLDoc('../tryckeri/affischer/priser/A3Priser.php')">A3</option>

      <option value="b1" onclick="loadXMLDoc('../tryckeri/affischer/priser/B1Priser.php')">B1</option>

      <option value="b2" onclick="loadXMLDoc('../tryckeri/affischer/priser/B2Priser.php')">B2</option>

      <option value="b2" ></option>

      <option value="offert" onclick="loadXMLDoc('../tryckeri/form/offertTryckeri.php')">Offert förfrågan</option>

    </select>

  </p>

  <br />

  <div id= "priser">

  </div>