Yes, yes, we know Microsoft rules; no other company will ever knock it off the top of the software mountain, etc., etc. History tells us that no business is immune to the decline of age and Microsoft is proving to be no exception.

You’ll find the latest proof of this at Net Applications’ January 2009 Web site usage numbers by operating system. There, you’ll see that Windows is continuing its slow fall from total desktop operating system domination.

Windows’ fall has been happening now since early 2008. Microsoft was running scared well before then though as Jim Allchin, former head of Microsoft’s Vista program, said in 2002, “we are not on a path to win against Linux.”

Then, in December 2008, Windows dropped below 90% of the desktop market for the first time since Windows 98 appeared. Now, Windows is down to 88.26%. Mac OS X is within touching distance of 10% and Linux is still hanging in there with 0.83%.

The news is even more dramatic if you look at Web browsers. Internet Explorer has been dropping at about .6% a month over the last twelve months. Internet Explorer is now down to 67.55%. The winners? Open-source’s application darling, Firefox with 21.53%, followed by Safari at 8.29% and Google’s open-source Chrome popping up over 1% at 1.12%.

It’s no coincidence that Microsoft just had its first major layoffs ever. Certainly, part of that is the economy, but on the other hand, Microsoft was in decline long before the market collapsed. Microsoft is showing its age, and it’s not pretty.