Did you ever wonder how to find out which Hotfix/Service Pack Level your ISA Server is currently running on?

In ISA Server 2004/2006 simply open an MMC on the ISA Server and Open Help -> About Microsoft ISA Server. Here you'll see the Version Number of your ISA Server (screenshot shows ISA 2006 SP1).

Another way to check out the Version number is to open the ISA installation directory and right-c