Virtualisation can benefit you with regards to ROI as well as simplifying IT's server management burden, it also plays a big part in saving energy and therefore helping the environment.

Hardware Virtualization uses software to create a Virtual Machine (VM) that emulates a physical computer. This creates a separate OS environment that is remote from the host server. By providing multiple VMs at once, this approach allows several operating systems to run simultaneously on a single physical machine.

Rather than paying for many under-utilized server machines, each dedicated to a specific workload; server virtualization allows those workloads to be consolidated onto a smaller number of more fully-used machines.

Other valuable benefits are listed below:

Reduce capital costs and operational costs.  By  consolidating  server footprints, which  in  turn  helps  lower  power  and  cooling  costs  and  saves space. Consolidating servers brings very real benefits with regards to the reduction of power and cooling, as well as real estate, requirements for the datacenter. This could potentially reduce energy use by up to 90%, therefore having a positive effect on the environment.

Enable disaster recovery solutions. By enabling OS portability, virtualization allows you to photograph and duplicate your production environments to collocation facilities or branch offices and, in the event of disaster, to quickly get back up on exactly the same operating environment in a matter of minutes without having to ship tapes or hassle with patch management.
Simplify server management burden. By enabling companies to easily move virtual machines from one physical server to the next, organisations can both save on management costs and reduce the burden on their IT staff.

Increase business agility. Virtualization will allow your IT staff to swiftly deploy and shift computing resources to accommodate your critical business applications.