I've tried the free personal version that is supposed to work with Vista. I had lots of problems that I erroneously assigned to Vista until I uninstalled this piece of crap software and everything worked perfect again. For example, I would load Yahoo Messenger and when I wanted to close it it wouldn't (right clicking its icon on the tray and choosing exit), and if I opened Task Manager Yahoomessenger.exe was still there, and selecting it and trying to kill it wouldn't work. The same happened with bittorrent and some other processes, and it also caused several minutes long delays on shutdown, all of which disappeared as soon as I uninstalled Zone Alarm. I installed the latest beta of Comodo firewall and everything works just fine.