Your user name and your email address are tied together. You can't change either, as far as I know, without asking Ed. If you were to try to change your user name but still using the same email address it would say that the email address is already in use (by your current user name). If you were to try to change your email address but still using the same user name, it would tell you that your user name is already in use (by your current email address). Or something like that! I think!