Here's a question for someone in business. I work part time for a small "mom and pop" business (major home appliances). They have 3 PC's on an LAN and one stand alone. All have internet access (AOL). None have a firewall. What would anyone recommend for a firewall? They do have anti-virus protection.
Besides Zonealarm, if you were trying to improve security, I would find out what they have for virus protection. My limited expereince with helping friends improve security is that they all have anti-virus software. However, when you check you frequently find that it hasn't been updated in months. Sometimes it is disabled. The software may be marginal quality like MacAfee. Lastly, they need some help in understanding how to handle email safely.