I agree with Carsten on this. It doesn't matter in the two instances he mentions, but otherwise I'm sure you would get emails from people telling you there is something wrong with your program because the numbers don't match.
Implemented as is would be ok, I would probably just hack out the "x Registered User(s)." text on my board, leaving the "x Anonymous User(s)." in as they can't be invisible, and this would eliminate any confusion.
Darren.
http://www.bullpen.com.au