Make my Exchange2k not a Open Relay Box?

My Exchanger is acting as a Open Relay. I’v tried every thing to stop it from doing that, I got a user respond to a previous question of mine, which put me on the right track, but doing all that is still not helping me solve the problem. As of now the exchange is set up as follows.
There are no connectors.
Virtual SMTP Server->Properties->Access Tab->
Authentication Button->Annonymous is checked,basic authentication is checked,Itegrated Wins Authentication is checked.
Under the Relay Button.
Only the list below option is selected. And the “Allow all computers which successfully authenticate to relay regardless of the list above” is checked.

With these settings, it is acting as a open relay box.

What do i need to do to stop it from acting as a “Open Relay Box” ?

Thanks alot