Commodore and PC was the same: based on games. You turned on your PC in 2002 to play games. Now? You turn on your PC to use internet: facebook, e-mail, msn, skype, news. What's going on?Microsoft hasn't got a talented leadership. In the company they thought the CONSOLE market is a good one for them. Not really: Console is the biggest enemy of the PC and Microsoft. What?
An original PC game GTA IV. released for console first. Turning-point... If you wanna play games you have to buy a console. How many have been released for PC this year? How many of them just "PC" games?
The evolution of the PC based on games: buy a new Video Card, bigger RAM, better CPU, mainboard. Now 2009 why should I buy? There is only few good PC game which actually will use it! You know what we think about Linux in 2002 : there is no game for it so that's why I use Win98. Now there is no game for PC. What we have is FLASH games which you can use any OS(mac,win,linux).
So because of 3-5 games you will not buy a new PC every year especially not a gamer PC which use 500-1000w power (hourly) and you will not use this kind of PC for check your e-mail, facebook or watch a movie. AND: you don't have to use WINDOWS to check your email, your facebook or watch a movie or play a FLASH game.
Microsoft you are good: you have changed the market!! Practically: Xbox killed your OS monopoly.
PS: Modern Warfare 2 is an example for PC needs: breaks record with 4.7 million in day-one sales (and it's works fine with Geforce 8800Gt which is a 2 year old one so it is also a good example: Windows's PC market is in trouble)