Re: If the figures regarding Mac sales are correct...
Well one of the reasons for declining Windows PC sales is not specifically Windows 8 - or even Windows 7 or even Vista. I am aware of many corporate entities who won't upgrade their H/W because it's still happily running XP - and at least half a dozen techiesI've spoken to in the last few months are unconcerned at the demise - as far as Redmond is concerned - of XP. I have heard comments like "We'll buy in support" and "Our firewall handles all our security".
Are they right?
Only time will tell - but when you're not running extremely testing software such as graphics packages, there simply isn't the pressure to upgrade.
As a previous commenter wrote, only graphics types, video types & gamers really need to chase the newest developments. Office 2007 running under XP continues to run as it always did - and that is sufficient for huge numbers of corporate users.