The Windows operating system had been sitting pretty with a 90 percent or more market share for ... well ... forever. Then November and December 2008 came along.According to Web metrics tracking company Net Applications, Windows market share declined 1.8 percentage points in November and December, its biggest two-month dip ever and double the previous record of .92 percent, which took place a year ago. Unfortunately for Microsoft, in the same two-month time period, Mac OS X set a record for increased market share, jumping above 9 percent for the first time, according to Net Applications, which bases its numbers on Internet usage and not sales.Results from holiday months like November and December are deceptive. More people were away from the office using home Macs to cruise the Internet with Firefox and\/or Safari. I would argue that most of the Windows and Internet Explorer market share reductions will be reversed in January and February when more people will be at work, sitting at PCs using IE. Nevertheless, the numbers are unprecedented and provide proof that the smaller guys are gaining on the software giant.Lately though, I see more and more of a division brewing: PCs\/Windows are for the workplace, Macs are for the living room. I say this despite Mac retail sales actually dropping 1 percent in November while PCs sales grew 7 percent. I think that was a reaction to Apple not cutting MacBook prices. The home\/office division idea is mostly my own anecdotal observation: I'm currently without a personal laptop, standing at the PC or Mac crossroads, and all I hear from friends and colleagues is: "Buy a Mac."But they're nearly twice the price! So what, they say. "It's a good investment. It's worth it. Buy a Mac."Buy a Mac. As if it's a quick fix for all of life's ills. As if it will make me smarter, cooler and more creative. That's the illusion Apple has been successfully shilling for years. But I digress. Yes, Windows usage is slipping but I don\u2019t put all my faith in Net Applications' stats because they are based on the number of people using Windows who browsed the Web sites that Net Applications monitors. Operating systems are hard to measure and I would not take Net Applications' numbers at face value.With that said, I will be surprised if Windows market share slips further in the next two or three months. I actually expect it to go back to October levels. But if it does continue to dip, then the whole "people were home more with their Macs in November and December" argument loses validity, and Microsoft will have something to worry about.