Virtualization becomes a very compelling technology to organizations running 5 servers, any more server virtualization should be your strongest choice.  Overwhelming benefits of virtualization include economic and high availability advantages.

Virtualization is one of the very few technologies that is a perfect "Go Green", it not only saves on electricity but also saves capital and operational cost for companies.  Virtualization has already started transforming computing as we kn ow it (at least as we used to know it).  Virtualization vendors has bundled their hypervisor software into servers, very soon all servers will be "hypervisor" enabled by default.  As more and more companies adopt virtualization, demand for virtualization skills from engineer to Administrators will increase (and we are already seeing it).