I am in favour of a completely separate website for CentOS , at www.centos.org , obviously linked to the caosity website.
This is the only way IMHO to avoid the current confusion.
This is even better, because it's true that once people hear about CentOS3, the fact that there is another distrib suggested, he is quite confused. To have a website completely dedicated to CentOS 3 is far better because these OSes are so different that they are worth having their own websites.
Kind regards,
Daniel