Establishing a connection via ssh (Putty) or VNC are two very different services, with completely different applications.
If you wish to establish a terminal like connection, then using Secure Shell (SSH) is the way to go, if you after a GUI/Desktop connection similar to as if you logged on direct to the Linux box with keyboard, mouse and monitor, then a VNC connection is what you are after.
First of all, is this a physical Ubuntu box or a VM running Ubuntu?
To establish a SSH connection, first make sure you've installed the SSH server on your Ubuntu box, which is a completely different package than that of SSH client commands you would typically use to connect from the Ubuntu box to the SSH server installed on another machine.
Run the following command within a terminal window on the Ubuntu box:
If the SSH server daemon is currently running on you Ubuntu box you should see output similar to the following:
If the above SSH daemon is not found, then install the SSH server using the following command:
sudo apt-get install openssh-server
The installation should also open the proper ports (port 22) on the Ubuntu box and start the sshd daemon.
If the Ubuntu system is a physical machine, you should then be able to connect with Putty by specifying a SSH connection (port 22) and the proper IP address of the the Ubuntu box.
If the Ubuntu system is a VM, like VMWare you will need to switch the VM network connection to bridge mode or further configure the default NAT connection which is configure by default. Switching to bridge mode is much simpler.
If you are still having issues establishing a connection, there maybe some firewall blocking the ports on either the Windows or Ubuntu system.
BigDog