Modeling your ISA firewall configuration and network in a virtual environment is critical before deploying the ISA firewall in a live environment. I never go to a customer engagement to deploy an ISA firewall without having done a proof of concept in my virtual lab. While I use VMware for this purpose, Microsoft Virtual PC can also be used. The good news is that Virtual PC is now FREE!
Check it out at: http://www.microsoft.com/windows/virtualpc/default.mspx
Thomas W Shinder, M.D.
MVP -- ISA Firewalls