What does it mean to have licensing rights to four virtual operating systems?
Customers who deploy Windows Vista Enterprise can install up to four copies of the operating system in a virtual machine for a single user on a single device. When paired with Virtual PC (available as a free download), this benefit provides the most economical way to address application compatibility and other scenarios through virtualization. Customers who do not deploy Windows Vista Enterprise and want to use the operating system in a virtual machine must purchase a license for every copy of Windows Vista that is installed in a virtual machine.