Because applications can't distinguish between a virtual machine (VM) and a physical machine, you can install and run your existing backup agents (or Windows Backup) on VMs. By doing so, you can back up these systems just as if they were physical systems on the network. Some backup software vendors are considering providing a backup agent that can back up live VMs, letting you secure the data of all VMs by running one backup job on the host system. No vendors currently support this functionality, but I anticipate that these types of solutions will be available within the next 12 months.