The Free VMWare Player software allows you to run multiple guest operating systems on top of a single host operating system.  There are many benefits to running Virtual Machines:

• Testing new Operating Systems
• Testing Applications across a range of Platforms
• Increased security and stability - if a guest VM is compromised or crashes, the host machine is unaffected.
• Increased Hardware utilization.  Most servers run at a load of 1% capacity or less.  By running multiple servers in VMs, hardware utilization can be increased, data center space freed up and electric & cooling costs decreased.
  
• Continued support of Legacy Applications - Many legacy applications were not designed for modern operating systems and may be incompatible.  Running the application in a virtual instance of the original target OS can extend the life of the legacy application.