function chkSubmit()
	{
		var returnValue = false;
		var card_number = document.forms[0].card_number.value;
		if (document.forms[0].card_name.selectedIndex == 0)
		{
			alert("You must choose your credit card.");
			document.getElementById("card_name").focus();
		}
		else if (card_number == "")
		{
			alert("You must enter a credit card number");
			document.getElementById("card_number").focus();
		}
		else if (card_number.length > 16)
		{
			alert("You haven't formatted the credit card correctly. No spaces please!");
			document.getElementById("card_number").focus();
		}
		else if (card_number.length < 15)
		{
			alert("You haven't given a valid credit card number - it is too short!");
			document.getElementById("card_number").focus();
		}
		else if (card_number != parseInt(card_number, 10))
		{
			alert("That does not seem to be a valid credit card number.");
			document.getElementById("card_number").focus();
		}
		else if (document.forms[0].exp_month.selectedIndex == 0)
		{
			alert("Please choose a month of expiration.");
			document.getElementById("exp_month").focus();
		}
		else if (document.forms[0].exp_year.selectedIndex == 0)
		{
			alert("Please choose a year of expiration.");
			document.getElementById("exp_year").focus();
		}
		else
		{
			returnValue = true;
		}
		return returnValue;
	}