Sun Micro's VirtualBox is an application that can be used to run a client operating system on another host computer. This application is one of the most powerful free virtualization software suites available today.
Prepare an ISO of the operating system (you can use the original DVD) and copy to a DVD or the host hard drive.
In order to Setup VirtualBox, start the application after its installation.
Click on New and follow the wizard setting the path to the ISO and naming the operating system. Make sure the hard drive has plenty of room for the operating system application. With hard drive space being inexpensive, your server operating system can easily use as little as 20 gb as a DHCP server or with as much space that is needed for the role of a file server.