I got a new PC with the Vista OS in mid-May. I tried several different firewalls trying to find one that worked well for me and that I liked the functions and user interface. I have used ZoneAlarm on several PC's for quite some time and have been happy and problem-free with it, but it was not available for Vista yet. My Vista machine came with a McAfee firewall which soon started throwing up various error messages and I've never been a big McAfee fan so I started looking at others. I tried Norton 360 for awhile and it worked very well, but I did not like the user interface for it at all for some reason and it was expensive, or so I thought.
As I didn't really liked the interface, I kept looking and tried the PCTools Firewall from pctools.com for awhile. I liked it okay too and it is freeware, but I had an ongoing problem with it and connecting to a wireless network printer I use alot and I never actually got that resolved. For some reason, that product seems to have disappeared from their website now, so I don't know if they have discontinued it or what happened there.
I looked at several others in the meantime and was willing to pay a premium price for one if I could find one that worked well with features and an interface that I liked for it. I kept up with the ZoneAlarm site and they released their Vista ready version so I decided to try it. In looking at their support forum, there are lots of users that have many issues with using ZoneLabs products, but I have never had any of those problems myself. I downloaded their latest free version for Vista and installed it problem-free about 3 weeks. It has been smooth sailing for me with it ever since and I'm happy now since I'm back to using a firewall I'm familiar with and one that has always worked well for me. Despite seeing alot of negative things posted about ZoneAlarm in several places, it has and still does work very well for me. I'm happy with it on my Vista machine and have had no issues of any kind with it.
I hope this helps.