function showHint(str,field)

{

	f=field+"Check";

	if (str.length==0)

	  { 

	  document.getElementById(f).innerHTML="";

	  return;

	  }

	xmlHttp=GetXmlHttpObject()

	if (xmlHttp==null)

	  {

	  alert ("Your browser does not support AJAX!");

	  return;

	  } 

	var url="script/checkusername.php";

	url=url+"?q="+str+"&n="+field;

	url=url+"&sid="+Math.random();

	xmlHttp.onreadystatechange=function() 

	{ 

			if (xmlHttp.readyState==4)

			{ 

				document.getElementById(f).innerHTML=xmlHttp.responseText;

			}

	}

	xmlHttp.open("GET",url,true);

	xmlHttp.send(null);

}

var xmlHttp=null;

function GetXmlHttpObject()

{

  var xmlHttp=null;

  	if (window.XMLHttpRequest) { // Mozilla, Safari,...

		xmlHttp = new XMLHttpRequest();

		if (xmlHttp.overrideMimeType) {

			xmlHttp.overrideMimeType('text/xml'); }

	} 

	else if (window.ActiveXObject) { // IE

		try {

			xmlHttp = new ActiveXObject("Msxml2.XMLHTTP"); } 

		catch (e) {

			try {

				xmlHttp = new ActiveXObject("Microsoft.XMLHTTP"); } 

			catch (e) {}

		}

	}



	if (!xmlHttp) {

		alert('Cannot create XMLHTTP instance');

		return false;

	}

  return xmlHttp;

}