If the option to send a notification to a new user is on in the Order Profile Page Settings, BUT for specific orders no new user account is created(ie, the user chooses to checkout without creating an account) this email is still sent, which seems a bit confusing.
 
More so, if you do want the notification on in general for users who do create accounts, there seems to be no way of stopping these unnecessary emails going to users who dont create accounts. More than anything, it would seem to confuse and panic them that exactly what they didnt want had in fact occurred (that viart had saved their details).