How to turn off vnc server (left over from pre-leopard days)

Under Leopard, I have a list of computers (and the airport extreme) under "Shared" in the sidebar of the Finder. One of these computers is the wife's iMac G5. I also have under "Shared" something called yoko_(imac-g5.local). Clicking it shows a single button for "Share Screen". Clicking this button brings up a dialog box with the following message: "The computer “yoko_(imac-g5.local)” is running a VNC server that does not support Screen Sharing keystroke encryption. Text you type to this computer may be intercepted over the network. Do you want to continue connecting anyway?" Well, not really.

Some time ago in pre-leopard days, I installed various vnc clients, trying to get remote access to the iMac G5. Apparently, Leopard kept this server open when I installed it over Tiger. But now that Leopard offers ways to do this, I no longer need to have this vnc server running on the G5 and would like to turn it off (and get rid of that superfluous reference in the sidebar).

So the question of the day is, short of doing an Archive and Install, how do I turn this VNC server off in Leopard? I can see no reference to it anywhere in Network, Firewall, or Sharing. Any suggestions, anyone?

Thanks!