Microsoft is loosening the reins on Vista licensing in an effort to let businesses try out some new computing possibilities, including "diskless" PCs.

For the most part, the Windows licensing terms have assumed that the whole PC is going to be in one place; however, increasingly, that's not necessarily the case.

Virtualization technology means that one physical computer can act as many separate computers, while higher-speed networks mean that different parts of a computer can actually be housed in various locales. For example, it is now possible to have a diskless PC, in which the main hard drive of the computer is actually stored in a data center, while all the other parts--processor, graphics chip and memory--remain at a worker's desk.

But until Sunday, there was no proper way to license Windows for such a computer. Under new licensing terms for Windows Vista Enterprise, businesses will be able to use the corporate edition of the operating system to handle this as well as other niche cases in which a PC's storage, computational power or both are handled somewhere other than the desktop.