I give the answer myself:
I managed to copy the files 'installing' openssh-server on live CD.
This is how I did it:
Ubuntu 8.04.1 Desktop live CD running.
Applications, Accessories, Terminal
Write down the data shown at "inet addr:"
Does not work due to no password for default user 'ubuntu' of the live CD specified.
sudo apt-get install openssh-server
Enter a password, I used ubuntu
Menu, Places, Connect to Server...
Service Type: SSH
Server: The "inet addr:" you found out using ifconfig.
I have been prompted to enter the new password ubuntu twice.
Nautilus will now show the usual list of folders and files of the first PC.
Open a second Nautilus Window in
and simply copy and past folders and files between the 2 nautilus windows.