I have been using the free version of Zone Alarm on all of my family's computers for years. It is kind of hard to find on Zone Alarm's website so here is the link to the download page for it if you are interested:

http://www.zonealarm.com/store/content/catalog/products/sku_list_za.jsp?dc=12bms&ctry=US&lang=en

Cheers!
Bill