Macs only need a HIPS..
vulnerabilities are rare enough in Macs, I would say a good file cleaner(if there is such a thing for Macs), and Rapport for Safari are good enough. The few malware that could end run such a system are covered in the Apple store as downloads for malicious file removers, when and if they rarely come up. I'm not saying Macs are like an Army tank, it is just that it takes less effort to secure them. But then it has taken less effort to secure new versions of Windows too. Just don't run as administrator! And of course anyone should be using a good password manager by now. The only difference with Windows is so many of the applications put holes in the system, you really need to keep up with the applications patches. My brother tells me this isn't a problem with Macs - if the app comes from the Apple store it already auto updates. Feel free to flame me, I am OS agnostic.
If you just want to keep Windows malware out of your email to protect others, then Clam X AV is good enough there, I suspect. No one should trust email now days - even coming from trusted contacts! Some Mac heads tell me they don't trust the built in firewall, so I'm sure there are good 3rd party versions out there that Apple will tolerate. Online Armor is one of my favorite Windows firewalls, I'm not sure what will run on a Mac that comes close to that kind of lock down.