function signupcheck()
{
    if (document.sign_up.email_address.value == "")
	{      
	alert("Please enter your email address.")      
	document.sign_up.email_address.focus();      
	return false;       
	}   
	if (document.sign_up.email_address.value.indexOf ('@',0) == -1 || document.sign_up.email_address.value.indexOf ('.',0) == -1)
	{
	alert("Your email address does not appear to be valid, please try again.")      
	document.sign_up.email_address.select();      
	document.sign_up.email_address.focus();      
	return false;  
	}
}