how do i redirect based on selection in jsp?

My form is :

<form name="redirect">
<select name="selection">
            <option value="">--------service--------</option>
            <option value="plumber.jsp">PLUMBER</option>
            <option value="electrician.jsp">ELECTRICIAN</option>
            <option value="carpenter.jsp">CARPENTER</option>
</select>
<select name="locality">
            <option value="">--------select--------</option>
            <option value="KOMMADI">KOMMADI</option>
            <option value="MVP">MVP</option>
            <option value="RTC">RTC</option>
</select>




 <input type=submit value="Go!" onClick="WinOpen();">  
</form>

and the javascript is

    <script language="javascript">
            function WinOpen() 
            {
           var url=document.redirect.selection.value;
            document.location.href=url; 
            response.sendRedirect(url);

            }             
    </script> 

The above code is not working for me..the page just refreshes instead of redirecting.. I want to redirect to page based on the selection value.And also send the locality parameter to the other page.plz help me out