Hyper-V is a great solution for consolidating physical servers that do not fully utilize the hardware that they are installed on. Even so, virtualizing may not be the best option when it comes to legacy servers.
One particular aspect of server virtualization that a lot of people seem to be interested in lately is legacy application consolidation. One of the issues that server virtualization was originally intended to address was hardware underutilization. In the past, corporations have often used a dedicated server to run an application that does not actually use all of the server’s resources. Virtualization allows a single physical to host multiple virtual machines, none of which would take full advantage of the server’s resources by itself.