function checkPostCode(){
	var arrPostcode = new Array("NN","MK","LE","SG","CB","PE","CV","B","OX","HP","AL","WR","WS","WV","DY","ST","LU","DE","NG");
	var obj = document.getElementById("checkResult");
	var postcode = document.getElementById("postcode").value;
	var trueMessage = '<img src=\'/images/accept.png\' alt=\'\' border=\'0\' />&nbsp;Yes - we can supply and install awnings in your area.';
	var falseMessage = '<img src=\'/images/cross.png\' alt=\'\' border=\'0\' />&nbsp;Unfortunately we cannot currently install awnings in your area. Our awnings are still available to purchase for self install.';
	
	document.getElementById('checkPost').innerHTML = '<img src="/images/loading.gif" alt="" border="0" />&nbsp;Checking';
	
	var available = false;
	for(var i = 0; i< arrPostcode.length; i++){
		if( postcode.toLowerCase().indexOf( arrPostcode[i].toLowerCase())== 0 ){
		available = true;
		break;
		}
	}
	
	setTimeout('changeAvailable(' + available + ',"' + trueMessage + '","' + falseMessage + '")',1000);
}

function changeAvailable(available, trueMessage, falseMessage){
	switch(available){
		case true:
			document.getElementById('checkPost').innerHTML = trueMessage;
			//do something
		break;
		case false:
			document.getElementById('checkPost').innerHTML = falseMessage;
			//do something else
		break;
	}
}