function submit_form(formName){
		var blnIsValid;
		var gFormName;	
		blnIsValid = false;
		gFormName = formName;
		blnIsValid = validate();
		// Determine if the form has been successfully validated
		if( blnIsValid ) {
			// The form has been successfully validated, so submit it
			document.forms[0].action = gFormName;
			document.forms[0].method = "post";
			document.forms[0].submit();
		}
	}

function validate() {
	return checkRent();
	return true;
}

function checkRent() {
	var iRent;
	iRent = document.forms[0]["txt_rental"].value;
	
	if (isNaN(iRent)) {
		alert("Monthly Rent must be a number and without the £ symbol");
		document.forms[0]["txt_rental"].focus();
		return false;
	} else {
		return true;
	}
}