Ending years of hype and anticipation, Microsoft chairman Bill Gates took the wraps off the software maker's long-awaited Windows 2000 operating system yesterday evening. Calling it "the most ambitious software project ever," he promised that the new OS will bring improved reliability, security and performance to a spectrum of computers from notebooks to powerful servers. "It's very exciting to be here today; this is a huge milestone for Microsoft and the industry," Gates said during a lavish presentation in which he was joined on stage by rock star Carlos Santana, Star Trek actor Patrick Stewart and a mock oversized notebook computer that filled almost the entire stage. End users who run Windows 2000 on notebooks and desktop computers will enjoy new levels of stability and reliability, Gates promised, addressing core criticisms that have been leveled at previous operating system releases from Microsoft. For businesses, the OS will provide a platform that matches the performance and scalability of popular Unix systems, but which can compete fiercely on price, he said. As Internet becomes "the standard platform for business and communications," companies will be able to use Windows 2000 to run highly available electronic commerce sites and large databases, Gates said. "This is a very, very rich product; it's a broad product," he said. The Microsoft chief offered the first public demonstration of Windows 2000 Datacenter, a high-end version of the OS due for release later this year, running on a 16-processor system built by Unisys. In another demonstration, literally hundreds of desktop PCs stacked high around the circumference of the auditorium were used to simulate a traffic flow of 1.3 billion hits a day directed at a rack of servers running Windows 2000 Advanced Server. The goal of the demonstration was to show that Microsoft's software is suitable for use in powerful servers used to run large databases and busy commerce sites, and manage thousands of PC clients - a lucrative market in which the software maker has long aspired to be a significant player. "We've taken a software approach to reliability and scalability that allows you to take any number of PC servers and combine them together to get a high volume of transaction support that's never been achieved before, keeping the value, choice and time to market" that Windows has to offer, Gates said. He highlighted products for the corporate market that will be introduced later in the year, including a 64-bit version of Windows 2000 designed for Intel's Itanium processor, an embedded version of Windows 2000 and BizTalk Server 2000, a server program that will rely heavily on XML (extensible markup language) for complex business transactions. Also in the works is Application Center 2000, which will help companies manage Web sites by monitoring the activity of Web servers, Gates said. While most of today's presentation emphasized Windows 2000's scalability at the high end, a Microsoft product manager also showed how the new OS can make life better for everyday users at work. Using infrared ports, users will be able to transfer large files wirelessly between two Windows 2000 notebooks placed side by side, the Microsoft manager said. The new OS also supports new power management features, as well as the ability to configure a new notebook over a network by downloading and installing a particular user's applications and files, he added. Gates also pointed to the results of recently published benchmark tests that he said reveal the stability and performance of Windows 2000. One test, conducted by ZD Labs, measured how long a Windows PC running a "strenuous" set of applications will keep going without crashing. Windows 95 lasted 2.1 days; Windows NT 4.0 kept going for 5.2 days, and Windows 2000 lasted more than 90 days, Gates said. Other, more technical, tests according to Gates, showed that an eight way server running Windows 2000 can offer better performance at a lower price than rival Unix operating systems, such as Sun's Solaris and Hewlett-Packard's HP-UX. Five thousand Microsoft engineers were involved in the development of the operating system, which cost the company around $2 billion (around £1,25b) to develop, Gates said. Two hundred and forty different notebooks, desktop PCs and servers installed with the new operating system are available today from manufacturers, he added. Microsoft executives and industry analysts have called Windows 2000 the most important operating system release in the company's history. Gates said today the OS will be the focus of the company's software development efforts for years to come. Outside the auditorium in downtown San Francisco where Gates delivered his speech, a carnival atmosphere prevailed. A calypso band played on the street for hundreds of conference attendees who circled the auditorium an hour before Gates' speech began waiting to get in. Microsoft representatives on rollerblades skated in and out of parked cars, with LCD (liquid-crystal display) screens strapped to their chest proclaiming the arrival of the new OS. Microsoft launched three versions of Windows 2000: Windows Professional, aimed at business desktops and notebooks, Windows Server, aimed at file, print, intranet and networking servers; and Windows Advanced Server, for larger servers running line-of-business and e-commerce applications. Customers upgrading from other Windows operating systems pay about half those prices. A fourth edition of the OS, Windows Datacenter Server, is expected to be released mid-year, and is the operating system Microsoft will target at hefty servers used for OLTP (online transaction processing), data warehousing and online service providers. Prices for that OS haven't been released yet.