You could just as easily get by with "set access for specific services and applications" on the remote server machine, as an FYI.
Are you attempting to VNC across the internet at large, or are you on the same local subnet? If you are trying to do this across the internet at large, you need to do some configuration to the router on the server end (which I am assuming is a home-based machine), as you have done.
Are you using Leopard for both client (local) and server (remote) machines? Then use the built-in Screen Sharing on the client machine in Finder. Just do a ⇧⌘k to browse the home network (if you are on the same subnet), click on the server machine, then click on Share Screen. Or you can do ⌘k and enter
vnc://remoteComputerName or
vnc://remoteComputer192.or10.IPaddress if local. If trying to do this across the internet, you would ⌘k and enter
vnc://yourDomainName (if you have a domain name for your home network like from noip.com or dyndns.com) or
vnc://yourRouter's_External_WAN_IPaddress. And you would need port forwarding set up in your home router.
If you don't have Leopard on both machines, and you have to use a VNC client like RealVNC Viewer or TightVNC or CotVNC or JollysFastVNC or..., then on the remote server Leopard computer, in its System Preferences Sharing, after you single-click on Screen Sharing and have checked the checkbox, make sure you click on Computer Settings... and click on VNC Viewers may control screen with password and enter a password that the client VNC program would use.
