The countdown began months ago. And now, the launch of Windows Vista -- Microsoft Relevant Products/Services's highly anticipated upgrade to Windows XP -- is just hours away. Microsoft is even running a countdown clock on its Vista-related blogs. At midnight tonight, the wait will be over.

On Tuesday, Vista will be available on store shelves across the country. It'll be sold as a stand-alone box of upgrade discs, and bundled as the OS powering countless new PCs. Users will have their pick of versions. Upgrading from Windows XP or Windows 2000 will cost $99 for the Home Basic version, $159 for the Home Premium, and $259 for the Ultimate version.

Executives from Microsoft, including CEO Steve Ballmer, are scheduled to appear at a Best Buy store in Manhattan on Tuesday morning to kick off the software launch. Best Buy is one retail outlet that will be heavily promoting Vista, with each of its 812 stores featuring interactive demos to give customers a better understanding of how the system Relevant Products/Services works.

Shiny and New

Industry analysts who have had months to play around with the new system have praised Vista's slick, streamlined interface and improved security Relevant Products/Services. Other standout features in the OS include new desktop search tools and, for laptop users, new options designed to extend battery life.

According to analyst Rob Enderle of the Enderle Group, Windows Vista is "simply more elegant." Excitement over Vista has been brewing for quite some time. Why? "It just feels newer," Enderle said. "My initial response is everything you used before just seemed old. Windows XP definitely seems old."

But, as with any new operating systems, there are a few glitches to deal with. Enderle said early adopters of the software should expect problems. The business Relevant Products/Services versions of Vista were released two months ago, and reports indicate that there are some driver conflicts and incompatibility with some older software.

Enderle said he expects 90 million Vista installs in 2007, of which a small percent will be installations on older hardware. He suggested that consumers wait 60 to 90 days before upgrading -- giving Microsoft time to respond to problems and roll out fixes, as needed. "By that point, the initial problems will be solved and they'll get a much better product."

Compatibility Woes

Another issue for Windows users is that Vista demands higher-end systems. Microsoft recommends that computers have at least 512 MB of RAM, an 800-MHz processor Relevant Products/Services, and 15 GB of hard disk space.

Bloggers testing early versions of Vista have been busily identifying problems -- and asking for users to keep the list going -- so they have a list to forward along to Microsoft to help iron out the kinks. One blogger who goes by the name of illdevilinc praised the new operating system on but also identified several glitches. He cited compatibility issues with AOL Instant Messenger, Firefox, Dreamweaver, and iTunes.

Microsoft is giving folks a chance to sound off on problems with Vista by posting both a call-in number on its Vista resource page, and a link for e-mail feedback.