The concept of virtual machines dates back to the 1960s. Both IBM and MIT developed operating system features that enabled user and peripheral time sharing, the underpinnings of which were early virtual machines. Modern virtual machines present a translation layer of system devices between a guest operating system and the host operating system executing on a computer system, while isolating each of the guest operating systems from each other. In the past several years, enterprise computing has embraced virtual machines to deploy a wide variety of capabilities from business management systems to email server farms. Those who have adopted virtual deployment environments have capitalized on a variety of advantages including server consolidation, service migration, and higher service reliability. But they have also ended up with some challenges including a sacrifice in performance and more complex system management. Some of these advantages and challenges also apply to HPC in virtualized environments. In this paper, we analyze the effectiveness of using virtual machines in a high performance computing (HPC) environment. We propose adding some virtual machine capability to already robust HPC environments for specific scenarios where the productivity gained outweighs the performance lost for using virtual machines. Finally, we discuss an implementation of augmenting virtual machines into the software stack of a HPC cluster, and we analyze the affect on job launch time of this implementation.