function initXhr () 
{
	var xhr = null ;
	if ( window.XMLHttpRequest )
	{
		xhr = new XMLHttpRequest() ;
	}
	else if ( window.ActiveXObject)
	{
		try
		{
			xhr = new ActiveXObject ( "Msxml2.XMLHTTP" ) ;
		}
		catch ( ex )
		{
			try
			{
				xhr = ActiveXObject ( "Microsoft.XMLHTTP" ) ;
			}
			catch ( ex ) {}
		}
	}
	return xhr ;
}