At last. At long last, there's a real challenger to the Windows desktop, and its name is Google Chrome OS.

Why is Google Chrome OS going to be real trouble for Windows? After all, technically, desktop Linuxes like Fedora, openSUSE, and Ubuntu, long ago left Windows in the dust. Mac OS X Leopard is also darn good and it and its upcoming successor, Snow Leopard, are easier to use than anything else out there. So, what's so special about Google Chrome OS? I'll tell you.

The most important single fact you need to keep in mind is that everyone who uses a computer already knows Google, and most of them trust it. Only PC power users know about Linux, and the ones who know what's what about such top-Linux desktop distributions as MEPIS 8 and Mint 7 are numbered in millions compared to the hundreds of millions who know Windows. Pretty much everyone knows Apple, but, even as Apple has gained some desktop market share, CEO Steve Jobs has never moved from his stand that Macs are high-end PCs. Apple builds sports cars, and it's not interested in selling you a truck, an SUV or, heaven forbid, a station wagon.

Everyone knows and can afford Google, though. They may not know much about Google Docs, but they trust Google for their searches and many of them are already Gmail users. You see, unlike the other alternatives to Windows, Google has the singular advantage of already being well known and well liked. That will make all the difference in the world.

That said, here's what else you need to know about Google Chrome OS.

It's Linux-based. It is not a simple presentation layer that vendors could put on top of Windows 7. Google will be delivering a complete desktop software stack -- Linux foundation, graphical environment, and Web-based application stack. The whole package will be open source. Google isn't saying which, if any, existing distribution it will be using for its foundation. Google certainly has the chops to roll its own desktop Linux. The desktop interface is not going to be either GNOME- or KDE-based. I'm told by sources, however, that it will be using the Portland Project's desktop APIs (application programming interfaces), which will allow existing Linux desktop applications like the groupware program Evolution and OpenOffice to work with Chrome OS. That said, Chrome OS is not a traditional desktop operating system, like Google's own desktop and device operating system, Android. It's a new kind of operating system that sits halfway between the old desktop operating system model and the newer idea of a Web-browser based operating system. At first glance, the idea of a Web browser as an operating system looks silly. It's not. With HTML 5's adoption, it's functionality has made it possible for Google to create Web-based applications that can work both off and online. Here's how it will work in Chrome OS. When you launch an application on the Web, say Google Docs, Chrome will use Google Gears to not only provide the ability to do work offline, but also to cache your online data in the open-source lightweight DBMS Sqlite. As a user, you'll never see any of this. You'll just find yourself doing most of your work in the Chrome browser interface. Once Google has this working really well, you may not even be able to tell when you're on the net and when you're not. I'm told off the record by Google engineers that the goal is to make the desktop invisible. You'll be spending 99% of your time in the browser. This isn't Android, is it? No, this is a different take on the desktop. Android is much more like Symbian on a smartphone or XP on a netbook. With Chrome OS, the plan is to bring Google's strong points, it's unparalleled collection of Web-based applications, straight to the desktop. This isn't the first time we've seen this idea. GOS (Good OS) used it first. What's different from the forthcoming Chrome OS and gOS 3.1 is the level of integration. GOS is a Linux desktop with a lightweight interface that uses many of Google's applications. Chrome OS is a Linux desktop that has Google's local infrastructure programs, like Gears and Sqlite, built in. When will we see it? Vendors are already working with Google to deliver netbooks with Chrome OS by the second half of 2010. Can't wait that long? Don't sweat it. I'm told by sources that bootable beta Chrome OS images will be available by this fall. How much will it cost me? Nada. Nothing. This is Linux and open source. Where Google will make its money is where it does now: online advertising and, as Chrome OS takes off in businesses, subscription fees to Google Apps. So, for businesses, instead of spending several hundred dollars a year, on average per user, for Windows, Microsoft Office, security software, etc., etc., you'll be able to pay a flat $50 a year per user for the whole office desktop kit and kaboodle.

Take Google's well-known and respected name, combine it with an unbeatable price tag, toss in Linux's unmatched security and stability, and what do you get? The most serious competition Windows has seen this century.

Steven J. Vaughan-Nichols has been writing about technology and the business of technology since CP/M-80 was cutting-edge and 300bit/sec. was a fast Internet connection -- and we liked it! He can be reached at sjvn@vna1.com.