I have all Apple equipment on a network behind an Apple Extreme router in DHCP+NAT mode. We are reasonably prudent about which websites we visit and which email links to click. Now on the scene is a friend with a Dell laptop running some flavor of Windows. You can probably guess where I'm going now. Yesterday she claimed her system had been invaded by some virus and nothing was working. Before coming to me, she called Microsoft support and paid $$$ for them to get rid of the problem. They warned her that the network she was on did not have a firewall. Only after that, she came to me, all bent out of shape. For reasons I can't go into, I can't tell her to go find another network to use. Is there something simple and FREE I can do to provide more security to her? Isn't there some sort of firewall right on Windows she can configure until her fingers fall off?