function valid(form)
{
    if (form.name.value=="" || form.firstname.value=="")
    {
        alert('Please give your name and your firstname !');
        return;
    }	
    if (form.mail.value=="")
    {
		alert('Please give your email address !');
		return;
    }
    else
    {
        var a=form.mail.value;
        var test="" + a;
        var val=0;
        for(var k = 0; k < test.length;k++)
        {
			var c = test.substring(k,k+1);
			if (c == "@")
			{
				val=1;;
			}
        }
        if (val == 0)
        {
          alert('Please give a correct email address !');
          return;
        }
    }	
    if (form.subject.value=="" || form.message.value=="")
    {
		alert('Please notify your request !');
		return;
    }
	
	if (form.capt.value=="")
	{
		alert('Please enter the code before submitting your form!');
		return;
	}
	
	// Comparaison des informations de captcha :
	$saisie = MD5(form.capt.value);
	$base = form.validcapt.value;
	if ($saisie != $base)
	{
		alert("The confirmation code doesn't match !");
		return;
	}
	
	// Envoi du formulaire :
	form.submit();
}