It's recently come to my attention that there are rogue PowerPoint presentations and other Internet accessible resources indicating that you should run security templates on the ISA firewall to "increase security". First, the ISA firewall doesn't need your security template to be secure, since if you've properly configured the ISA firewall you don't need to worry about local host based service exposure. Second, you should never run security templates that haven't been specifically designed to work with the ISA firewall itself.
If you want to play with security templates and hardening of the ISA firewall, then check out the Security Configuration Wizard.
Here's a great article that will introduce you to the wizard: