Leopard has a nifty VNC implementation built right into the OS, you can share your screen from the Sharing preferences and connect to it using any VNC client. And there is a VNC client built right into the finder ⌘-K (Connect to server) allows you to enter in a vnc server in the form vnc://server:port.
But if you try and connect to an up to date Xvnc server it will probably fail, you need to specify that your VNC server uses the VNC protocol 3.3 for backwards compatibility, the command option is simply “-Protocol3.3” you will now be able to connect to your Xvnc server from Leopard using the built in viewer.
If you were to follow my earlier instruction for a GDM VNC Server then simply add this option to: /etc/xinetd.d/vnc
You will notice that the connecting to server box doesn’t go away, this is because Apple does not like the option: -securitytypes=none
Setup a password file using vncpasswd and remove the above option and add the option: