Assuming you're using bridged networking with your virtualization software, Enterprise Vault won't care whether it's in a real or virtual environment. I've seen many implementations where several of the nodes are physical and several are virtual, which is especially common for environments that are transitioning to full virtualization but haven't completed the process yet.
If the virtual machine is sized properly, you shouldn't even see much in the way of performance hits.
Best of luck with your implementation. It should work just fine.