You\u2019ll see a lot of stories about Microsoft\u2019s next-generation of Windows, code-named Longhorn, popping up during the next couple of days. Jim Allchin, Microsoft\u2019s group vice president for platforms, has been on the road with a recent build of the OS and an updated message designed to get The Media (mea culpa) chatting anew after a period of relative quiet. Oh, and in the interest of making even more noise, HAPPY 20th BIRTHDAY TO WINDOWS!! (Microsoft will be repeating that theme as well.)In a nutshell, here\u2019s what you need to know about Longhorn.1) It\u2019s a long, long ways off. Microsoft is sticking to its claims of a 2006 ship date for the client version, but they\u2019re describing it as "Holiday 2006," which means they could declare victory over slipped schedules even if CompUSA employees are stocking shelves with boxes covered in shrinkwrap so fresh it burns their fingers as the strains of Auld Lang Syne are coming from the TV in the employee breakroom.And the server version will ship sometime in 2007. That\u2019s two years, which is great news for developers who have to get up to speed on the new Longhorn development tools and then need to update their applications in time to piggyback on the millions of marketing dollars Microsoft will undoubtedly spend on the launch. As for me, I\u2019m going to celebrate a couple of birthdays myself before I start making any upgrade plans.2) Longhorn is slick: Have no doubt. The user interface positively glitters, with cool fade effects, transparent title bars and the like. This is all thanks the the much-hyped Avalon interface engine, otherwise known as "The Graphics Card Vendor\u2019s Best Friend" because of the hardware you\u2019ll need to take full advantage of the system. (Microsoft was demoing Longhorn on one of those shiny red Ferrari-themed Acer notebooks, complete with an AMD Athlon 64-bit processor. I\u2019m always more impressed when people demo on something more realistic, though given the timeline, you may not be able to buy a 32-bit machine other than used on eBay by the time Longhorn arrives) And the search features I saw put XP\u2019s file-finding functions to shame. Forget about folders, now you get customizable views. Just start typing and documents begin to appear. Add keywords. Categorize. Group by creator. By Date. Heck, sort \u2019em by color, scent and favorite movie. Search through metadata that Windows will automatically generate based on content. The search feature alone would be worth the upgrade\u2014if Microsoft were releasing Longhorn now. But the competition\u2014including X1, Google, and Yahoo\u2014have a couple of years to build all these features and more into their own products, which will undoubtedly negate some if not all of Microsoft\u2019s advantage.3) Longhorn will be all about extensibility. XML runs rampant throughout the platform, and developers will supposedly be able to use Longhorn\u2019s openness to quickly enhance existing features and build new ones. Only time will tell exactly how "open" Microsoft ultimately will be, but at least it appears to be taking a couple of steps in the right direction. I\u2019m not holding my breath in expectation that Redmond will break its eternal tradition of "open...but"\u2014though we can always hope.4) It\u2019ll be the most secure Windows yet. Somehow I think IT managers are going to get a little tired of having this drum banged in their ears from here to eternity (shouldn\u2019t the operating systems they\u2019re buying now be secure?), but get used to it. With Longhorn, Microsoft will change some core functionality in Windows\u2019 security model. In XP for instance, the vast majority of users run as administrators. Why? Because XP pretty much divides all users into one of two groups: "Administrator" and "Virus" (aka, "User"). (Heck, some viruses actually have more privileges in XP than do standard "Users"\u2014thus the need for XP SP2). In Longhorn, IT admins will be allowed to get much more granular. They\u2019ll be able to restrict everyday users from seriously dangerous activities while still letting them get their jobs done, say by enabling a wireless interface when they need to access their e-mail from a hotel room without it involving 30 minutes with the help desk. Individual applications will also be able to get their own security level. So an administrator could be doing disk management on a system while her browser window hums away at a lower level, hopefully eliminating\u2014or at least making more difficult\u2014a number of now-common attacks.5) Longhorn will be the foundation for the next ten years of Windows. This goes a long way in explaining why Microsoft is taking such pains\u2014and causing such delays\u2014this time around. I honestly believe they don\u2019t want to go through this process again if they can avoid it.Trying to power-lift everything\u2014the development tools, SQL Server, the client and server operating systems\u2014to the next level has proven a serious challenge even for the most mighty software development organization on the planet. WinFS\u2014once the third leg of the Longhorn stool\u2014is gone for now. And Allchin readily admits that Microsoft has even more issues it must address if it is to fully achieve its vision for Longhorn\u2014issues that don\u2019t have obvious answers. (One feature, for instance, would make it easy for users to suck everything\u2014OS, applications, data and all\u2014from an old machine to a new one. But how does Microsoft deal with the licensing issues for software keyed to a single machine? Allchin doesn\u2019t know yet.)The fact that Windows XP is actually pretty solid right now will only work against Microsoft if Longhorn doesn\u2019t end up being something really special. (Why upgrade if you\u2019re quite comfortable with what you have?) Botch something this complicated, and Microsoft could spend the rest of its days as little more than a support organization dedicated more to issuing patches than to advancing its technology agenda. Twenty years of Windows. Impressive. But the next couple of years will determine if the timeline continues for another decade.