What is it? Younger brother of the Windows desktop computer operating system with which most PC users are familiar and the system which Microsoft hopes will become the first choice of big business.

What's at stake? The multi-million-pound business of the world's major enterprises.

The main rivals: Novell Netware, various versions or "flavours" of Unix, IBM and Sun Microsystems' Java.

Is Microsoft on its own? No. Competitors like Hewlett-Packard and DEC have become its bed-partners in the project.

What's new? Unisys, better known for its mainframe and midrange computing products, has come on board to boost NT's performance in its areas of enterprise weakness.