I think it would really come down to the person running the network. People using either operating system for a long period fo time would know how to get the most performance out of that operating system in its respected applications.

Being a gamer, i know how to get the most performance out of my xp box, because ive used windows and dos all my life.

But i want to learn linux as well because that makes you flexable, you can use linux on the machines where they will be the most useful. Same with windows.

The point is making the best network possible right? that shouldn't mean picking the best os for the whole job, it should mean the best os for the task needed.

But im still new at this, so take that with a grain of salt.