The latter isn't as good as ZoneAlarm, but it's still pretty good. If your Mac is plugged into a network, you need this or an equivalent product. There are a few others out there as well, but firewall technology is largely a new area. So do your due diligence, and expect some surprises, including slashed prices. Another home option is a hardware gateway.
Several vendors make ethernet gateways for home use.
Here's how they work. On one end there is a single network or dial-up modem connection, to which you connect the internet. Whether you use ISDN, cable, DSL, or dial-up is kind of irrelevant. The point is, you're connecting to the internet. The gateway in turn assigns a private internet address to each of the computers you own.