Does it need it: no.
Can you use it: yes.

First, install ubuntu.
Second, run the apps you want to run.
Third, install Firestarter.
On the Status tab of firestarter down at the bottom take note of the apps ports
that are in use.
On your modem close all the ports except those that are show on the status tab.

For example:
App Port
Firefox 80
gaim aol 5190
gaim mmcc 5050
gaim xmpp 5222

Unless you need to be more secure - then close the chat ports.