Internet Security 2014 claims that the OS is incompatible when I try to install on Vista 64-bit Home Premium. Why is this when Internet Security 2011 will install?
NikK is right. The supported platforms are Windows 8.1 / 8.1 Pro, Windows 8 / 8 Pro, Windows 7 (all editions), Windows Vista (SP2), Windows XP (32-bit, SP3 or later).
I'm guessing it's the OS service pack (SP). For 2014 and Vista, SP 2 is required.
In 2014 the firewall solution is based on Windows Firewall. 2011 had F-Secure's own firewall. I think that's the biggest difference, and maybe why SP 2 is required now that the Windows firewall is used instead.
Thanks, you're correct, it did need SP2. It's just a pity that F-Secure's error message wasn't more helpful.