I've often wondered about how this holds up in real life, performance wise. Don't get me wrong, I couldn't live without VMs and the theory of "network in a box" (so to speak) is sound but my use of VMs is almost completely for testing purposes and it's rare that I run more than one at a time. Does your guy have general specs for how a "decent" physical server is defined that would host 3 or more VMs?