function login()
{

	//Inicialização Ajax	
		var ajaxRequest;  // The variable that makes Ajax possible!	
		try
		{
			// Opera 8.0+, Firefox, Safari
			ajaxRequest = new XMLHttpRequest();
		} 	
		catch (e)
		{
		// Internet Explorer Browsers
			try
			{
				ajaxRequest = new ActiveXObject("Msxml2.XMLHTTP");
			} 
			catch (e) 
			{
				try
				{
					ajaxRequest = new ActiveXObject("Microsoft.XMLHTTP");
				} 
				catch (e)
				{
					// Something went wrong
					alert("Browser não compatível");
					return false;
				}
			}
		}		
		//Fim init ajax
		
		
		// Create a function that will receive data sent from the server
		ajaxRequest.onreadystatechange = function()
		{			
			if(ajaxRequest.readyState < 4)
			{
				var ajaxDisplay = document.getElementById('ajaxDiv');
				ajaxDisplay.innerHTML = '<img src="imagens/ajax-loader.gif" width="16" height="16"/> Carregando...';
				
			}
	
			
			if(ajaxRequest.readyState == 4)
			{
				if(ajaxRequest.status==200)
				{					
					var ajaxDisplay = document.getElementById('ajaxDiv');	
					
					
						var resposta = ajaxRequest.responseText;					
						if(resposta=="1")	
						window.location="home.php";					
						else
						ajaxDisplay.innerHTML = "Dados inválidos";
						
				}
			}
		}
				
		var login = document.getElementById('login').value;	
		var senha = document.getElementById('senha').value;			
		var queryString = "login="+login + "&senha="+senha;
		ajaxRequest.open("POST", "checa_login.php", true);
		ajaxRequest.setRequestHeader("Content-type", "application/x-www-form-urlencoded");	
		ajaxRequest.setRequestHeader("Content-length", queryString.length); 
		ajaxRequest.setRequestHeader("Cache-Control", "no-store, no-cache, must-revalidate");
		ajaxRequest.setRequestHeader("Cache-Control", "post-check=0, pre-check=0");
		ajaxRequest.setRequestHeader("Pragma", "no-cache");
		ajaxRequest.send(queryString);
		
}