function validateZip() {
	if (isNaN(document.zip_search.zip.value)) {
		alert("Please enter a five digit number for the Zip code.");
		return false;
	}
	else {
		if (document.zip_search.zip.value.length < '5') {
			alert("Please enter a five digit number for the Zip code.");
			return false;
		}
	}
	
	return true;
}