function ajax_check_user(login, span_id) {
	if (login.length == 0) {
		document.getElementById(span_id).innerHTML = '';
		if (document.all) document.getElementById(span_id).setAttribute("className","");
		else document.getElementById(span_id).setAttribute("class", "");
	}
	else {
		if (login.length <= 20) {
			var handlerFunc = function(t) {
				var xmlDoc = t.responseXML;

				if (document.all) var noeud = xmlDoc.childNodes[1];
				else var noeud = xmlDoc.childNodes[0];

				nom_noeud = noeud.nodeName;

				if (nom_noeud == 'check_login') {
					var check_login_xml = xmlDoc.getElementsByTagName('check_login')[0];

					if (check_login_xml.getAttribute('check') == '1') {
						document.getElementById(span_id).innerHTML = 'Ce pseudo est disponible';

						if (document.all) document.getElementById(span_id).setAttribute("className", "success_texte");
						else document.getElementById(span_id).setAttribute("class", "success_texte");
					}
					else {
						document.getElementById(span_id).innerHTML = 'Ce pseudo est indisponible';

						if (document.all) document.getElementById(span_id).setAttribute("className", "error_texte");
						else document.getElementById(span_id).setAttribute("class", "error_texte");
					}
				}
			}
			new Ajax.Request('/ajax/inscription/check_login.php', { method:'post', postBody:'login=' + login, onSuccess:handlerFunc});
		}
		else {
			document.getElementById(span_id).innerHTML = 'Ce pseudo est trop long';

			if (document.all) document.getElementById(span_id).setAttribute("className","error_texte");
			else document.getElementById(span_id).setAttribute("class", "error_texte");
		}
	}
}