If the guy has that much sensitive information on his system I would suggest buying a router, setting up some ACLs, and keeping the IOS udated. I would also suggest purchasing a Catalyst switch, and setting up some VLANs. Forget a software firewall, buy a Cisco 2500 or something of that nature, buy a router off of Ebay, thats basically all you need. And disable unused network services. Check for viruses, prefer. trojans.