Microsoft has released licenses for the Windows Vista operating system that dramatically differ from those for Windows XP in that they limit the number of times that retail editions can be transferred to another device and ban the two least-expensive versions from running in a virtual machine.
The new licenses, which were highlighted by the Vista team on its official blog Tuesday, add new restrictions to how and where Windows can be used.

"The first user of the software may reassign the license to another device one time. If you reassign the license, that other device becomes the "licensed device," reads the license for Windows Vista Home Basic, Home Premium, Ultimate, and Business. In other words, once a retail copy of Vista is installed on a PC, it can be moved to another system only once.

The new policy is narrower than Windows XP's. In the same section, the license for Windows XP Home states: "You may move the Software to a different Workstation Computer. After the transfer, you must completely remove the Software from the former Workstation Computer." There is no limit to the number of times users can make this move. Windows XP Professional's license is identical.

Elsewhere in the license, Microsoft forbids users from installing Vista Home Basic and Vista Home Premium in a virtual machine. "You may not use the software installed on the licensed device within a virtual (or otherwise emulated) hardware system," the legal language reads. Vista Ultimate and Vista Business, however, can be installed within a VM.