Also, which of the firewalls will be the least restrictive? This is my husband's computer and when I've tried firewalls in the past, he has complained about them. Would it be just as effective if we purchased the full version of Malwarebytes?
Third party firewalls can be very restrictive, especially when you first start using them. They are pretty much all the same but it's the price one must pay for the extra security. If you do on-line bank or other financial transactions on-line they are almost a must to protect your personal information and your money. If you don't, then the regular MS firewall will suffice especially in Vista and Windows 7. The full version of Malwarebytes is a good investment but no substitute for a firewall.