One day after chairman Bill Gates talked up the successor to Windows 2000, Microsoft revealed to a select group of testers the first "preview" of its next Windows release, code-named Whistler. Microsoft posted to a private download site Thursday build 2250 of Whistler Personal and Professional, according to testers. Build 2250 is the same build that Microsoft was demonstrating to attendees of its Professional Developers Conference in Florida this week. Gates told PDC attendees to expect Microsoft to ship Whistler in the second half of 2001, several months later than the company originally anticipated. Whistler is expected to be a fairly minor update to Windows 2000. A first Whistler beta is expected around September. The next major Windows release, code-named Blackcomb, isn't due out until the second half of 2002. While it toils on the next versions of Windows, Microsoft is simultaneously preparing to deliver its first Service Pack (SP1) update to Windows 2000 next week, testers added. It is not expected to release SP1 to retail, but instead will slipstream it into future product releases, as well as make it available to existing customers in the Windows Update site. Microsoft's timing for making Windows 2000 SP1 couldn't be more appropriate, since the company will announce its fiscal Q4 earnings next week. Some Microsoft watchers claim that Windows 2000 sales, while strong, haven't lived up to expectations. A number of large corporations have said they planned to hold off on deploying Windows 2000 until Microsoft released the first set of fixes and patches to the operating system. Microsoft told beta testers earlier this week to expect SP1 within a week. According to a note Microsoft sent to testers, SP1 is "a collection of fixes in the following areas: operating system reliability, application compatibility, setup, and security. SP1 is not considered a required upgrade. Microsoft recommends that customers review all available SP1 documentation and determine whether to install SP1," the note added. Microsoft declined to comment on features or availability of either Windows 2000 SP1 or Whistler. A spokeswoman said that Microsoft considered Windows 2000 sales strong -- recently passing the three million mark -- regardless of the availability of the first service pack update. Despite Gates' comments earlier this week about some of the planned Whistler features, Microsoft declined to comment on the alpha release made available Thursday. Gates said Whistler will be the first Microsoft operating system to feature some of the .Net user interface enhancements that Microsoft has on tap. .Net is the catchall name for Microsoft's next-generation, XML-enabled software products and services. According to the release notes included with Whistler 2250, testers said Microsoft acknowledged it is dropping AppleTalk, NetBEUI and DLC legacy networking protocol support from the operating system. The release notes also stated that Microsoft is adding IPv6 networking support to the release, as well as support for user-selectable "Visual Styles". Microsoft is expected to offer Whistler in a variety of consumer and business flavours, as well as in both 32-bit and 64-bit versions. See a screenshot preview of Whistler. What do you think? Tell the Mailroom. And read what others have said.