conflicto de la librerias jquery y prototype

[esaenz22]

buenas. hay proyecto k ya esta desarrollado y colocaron librerias de prototype. implemente un jquery para un formulario de login. pero cuando le doy a un vinculo para k me muestre el formulario login, de ja de funcionar.

he colocaldo el metodo jQuery.noConflict(); para evitar problemas de esas 2 librerias.pero aun asi no funciona ljqueyr con ajax.

me pueden orientar en ello por favor ?.

Código HTML:

<script src="js/prototype1600.js" language="JavaScript" type="text/javascript"></script>
<script src="js/scriptaculous/scriptaculous.js?load=effects,builder" type="text/javascript"></script>
<script src="js/alt.js" language="JavaScript" type="text/javascript"></script>
<script src="js/preview_templates.js" language="JavaScript" type="text/javascript"></script>
<script src="js/loader.js" language="JavaScript" type="text/javascript"></script>
<script language="JavaScript" type="text/javascript"><!--
Event.observe(window, 'load', function() {
  initAlts();
});
// -->
 
</script>
<script type="text/javascript" src="js/jquery-1.4.2.min.js"></script>
<script>
jQuery.noConflict();
</script>
 

el jquery ajax.

Código Javascript:

function login(){
    $.ajax({ 
        url: "login.php",
        type: "GET",
        beforeSend: function(){$("#customer_login").hide("fast");}, //show loading just when link is clicked
        complete: function(){ $("#customer_login").show("fast");}, //stop showing loading when the process is complete      
        success: function(datos){   
            $("#customer_login").show("slow"); //animation
            $("#customer_login").html(datos);
        }
    }); 
}
 
function validar_login(){
    
    var username = document.getElementById('username').value;
    var password = document.getElementById('password').value;   
    
    $.ajax({
        contentType: "application/x-www-form-urlencoded", 
        url: "validar.php",
        type: "POST",
        data: "submit=&username="+username+"&password="+password,
        beforeSend: function(){$("#customer_login").hide("fast");}, //show loading just when link is clicked
        complete: function(){ $("#customer_login").show("fast");}, //stop showing loading when the process is complete      
        success: function(datos){   
            $("#customer_login").show("slow"); //animation
            $("#customer_login").html(datos);
        }
    }); 
}