function makeRequest(url,div)
{

    document.getElementById('control').value=div;

    var n_url=url;

    document.getElementById(div).innerHTML="Cargando...";
    http_request = false;

    if (window.XMLHttpRequest)
    { // Mozilla, Safari,...
        http_request = new XMLHttpRequest();
        if (http_request.overrideMimeType)
        {
            http_request.overrideMimeType('text/xml');
        }
    }
    else if (window.ActiveXObject)
    { // IE
        try
        {
            http_request = new ActiveXObject("Msxml2.XMLHTTP");
        } catch (e)
        {
            try
            {
                http_request = new ActiveXObject("Microsoft.XMLHTTP");
            } catch (e) {}
        }
    }

    if (!http_request)
    {
        alert('Falla :( No es posible crear una instancia XMLHTTP');
        return false;
    }
    http_request.onreadystatechange = alertContents;
    http_request.open('GET', n_url, true);
    http_request.send(null);
}

function alertContents()
{

    div=document.getElementById('control').value


    if (http_request.readyState == 4)
    {
        if (http_request.status == 200)
        {
            document.getElementById(div).innerHTML=http_request.responseText;
        }
        else
        {
          alert('Hubo problemas con la petición.');
        }
    }
}

function isNumber(obj)
{
    if(isNaN(obj.value))
    {
        obj.style.border = '#c10f0f solid 2px';
    }
    else
    {
        obj.style.border = '1px solid #7f9db9';
    }
}