From: Rhoadesville, VA
I'm not sure if you realize it, but Virtual Server is limited to ONE processor.
It doesn't take much traffic at all to overwhelm ONE processor in ISA - especially with all the writing to the log files for each packet transferred.
As somone who runs Virtual Server (as well as VMware), I wouldn't recommend running your firewall on a virtual server. I'm got Virtual Server running on two production servers and I've hit limitations quite a few times (one is running 8 virtuals and the other 5 virtuals on dual processors with hyperthreading (shows up as 4 processors in base o/s).
VMware will let you use more processors and is probably a better choice for running ISA.
I wouldn't recommend rolling out ISA as a virtual machine in a production environment unless you don't anticipate ANY growth.
BTW, why are you trying to use this type of arrangement? Is it for testing or possibly for dedicated servers for customers?