Hey there Richard,
I agree with Cal, especially with the list of programs..
Dont waste your time with the MS windows firewall, some people say it's better than nothing, but I might just disagree with that!..LoL
Use ZA on all your box's, it's free and it's proven to work pretty well.. it isnt perfect, but it's better than what you get with windows!
Microsoft Antispy though, *IS awesome!, go grab that if you dont have it yet, so far I would have to agree, it is one of the best..
Add protection to each PC on your network, if the box gets plugged into an ISP in any way..protect it...