I've been using Zone Alarm for a while now (only about 2 years or so on the current PC I'm using) as well, the main thing I like about Zone Alarm (the free version too) is that it can also be used for other things such as finding out which program is trying to dial-up to the internet (ZA is so good that it reports that as well...), and I believe many have been helped by Zone alarm in those ways. And it also does what it was designed to do.

I would say that you should give it a try, chances are that you won't be dissapointed.