I am not able to help you with the SAMBA setup, I am struggling through that as well. However, I have got vnc to work.
In a console type 'vncserver',
it will prompt you for a password,
enter & confirm that & you are all set.
There are many options you can set with vncserver such as display #, (the default is 1) There is documentation here.
http://www.tightvnc.com/docs.html
also here
http://www.realvnc.com/documentation.html
As for connecting from the xp client, when you start the vnc viewer & it asks for the vnc server, enter ipaddress:display. You can use the host name if you have DNS or host files setup in your network. One other thing I have found, whoever you start vncserver as is who you are logged in as when you connect with vnc viewer.
Hope this helps.