Re: * another important factor is "Is it OK to install Active directory on VM? ".
Yes, I saw some companies put Domain controller on VM.
But: you must handle traditional Active Directory Problem.
You must understand the good is that VM can vmotion easily on such platform. It won't be shutdown by ESX.
The drawback is : DC could shutdown by other reason(e.g. by patching or Virus).
And together vCenter sometime relies on DC to login.
When DC is down by some reason, you may still need to login to vCenter for troubleshooting.
That's why,
When you configure your ESXi, don't forget to let Root Login and configure VMs.
If your environment scale-out later on , you can consider setup next DC Vitrual machine.
once again, becareful when you handle permission and credital problem.
Re: Exchange server
Once again, I suggest 2 Exchange Server, so that some more memory will be used.
This is up to you becasue if you have one exchange, the other ESX would work as a stand-by becasue resource is left and no one use.
You don't ask hardware question. So I assume that you know you better need a share storage.
MC
(from Hong Kong)
