function criaAjax()
{
	var objAjax;
	if (window.XMLHttpRequest)
	{
		objAjax = new XMLHttpRequest();
	}
	else if (window.ActiveXObject)
	{
		try 
		{
			objAjax = new ActiveXObject('Msxml2.XMLHTTP');
		}
		catch(e1)
		{
			try
			{
				objAjax = new ActiveXObject('Microsoft.XMLHTTP');
			}
			catch(e2)
			{
				alert('AMIGAO TROCA O BROWSER');
				return false;
			}
		}	
	}
	return objAjax;
}