When you say your computers are running through a hub you mean that your connected on a network using a hub..?
One of your two computers will be controlling access to the internet, ie one of the computers must be on so the other one can access the internet.
Remove PC Cillin Firewall, it's total crap download Sygate Personal Firewall and install that on the pc that connects to the internet, ie dials up via model/dsl.. if on cable it will just be the pc that has the Cable Modem attached to the PC, or the PC that has to be on for the other computer to have internet access.
When you suggest a hub has a firewall you are getting confused with a router, routers have built in firewalls, however its always a good idea to have a software firewall such as Sygate Personal Firewall.