According to MS and other articles that I have read they recommend that you have 2 VM's if you are going to Virtualize Exchange. One server for the Mailbox role and one for the CAS and Hub Transport server. We are a small shop with 20 users. We can split the setup if need be but I am wondering if it is nessacary with so few users. We have a Dell R710 with Dual Procs and 36gb of Ram running 2008 R2 Core so it is plenty powerfull enough. Any thoughts??