I can speak from experience when I say that PC hardware refresh cycles get extended when money is tight. Businesses judge that a four-year-old PC is good enough for now, so they aren't going to replace it yet. Besides, most businesses are ignoring Win8 just like they did Vista.
We've seen this same kind of market softness before, and a good economy always brings demand back. Tablets are part of the equation, but there aren't many users who are actually replacing a desktop with one.
I think that's a large part of it. Another aspect is that more and more folks who only use computers for web and email are going to tablets and smartphones instead of desktops and laptops. "Pro" users still need full-fledged computers, but "content consumers" are going with lighter weight options.
>>Besides, most businesses are ignoring Win8 just like they did Vista.
There are good reasons for that. Win7 + Office 2010 is pretty darn good on anything close to decent hardware. Win8 threatens to be a high learning curve “upgrade” for the user base.
Why jump right in when what you have works fine and the “upgrade” has dubious benefits?