function createRequest() 
{
	var request = null;
	try 
	{
   	request = new XMLHttpRequest();
	} catch (trymicrosoft) 
		{
	    	try 
			{
		    request = new ActiveXObject("Msxml2.XMLHTTP");
			} catch (othermicrosoft) 
				{
			    	try 
					{
    	    		request = new ActiveXObject("Microsoft.XMLHTTP");
			    	} catch (failed) 
						{
			        		request = null;
					    }
			    }
		  }

	if (request == null) 
	{
		alert("Error creating request object!");
	} 
	else 
	{
    	return request;
	}
}

var request = createRequest();