Here is what he has to say:
Hi Adam, unfortunately ZoneAlarm does not fully support Vista. Although ZA claims to run on Vista, it denies any installation approaches on Vista 64 bit versions.
It has already taken them quite a while until they could adapt the software to Vista (32bit), because they face some major difficulties in implementing their firewall app in the new OS. Therefore, it is questionable if ZA can keep up the high standard. I truly hope that ZA will stay among the best in the market. However, hopefully the 64bit version will come out soon.