If you’re on Windows XP, Windows Vista or Windows 7 — and if you’re reading this site and a human, you better be at least — upgrading to Windows 8 is going to be dirt cheap: only 40 bucks for a digital download in 131 countries, including Australia.
The $40 upgrade price for Windows 8 Pro lasts from the Windows 8 launch (sometime later this year) until January 31, 2013. The way the cheapo upgrade works is through Windows 8 Upgrade Assistant, which will give you step-by-step instructions on how to install and check your PC to see if you meet up to the system requirements. If you hate downloading software and/or collect DVDs, you can get a retail copy of Windows 8 for $70 during this promotion period. Either way, it’s going to be very affordable to upgrade to Windows 8
http://www.gizmodo.com.au/2012/07/upgrading-to-windows-8-will-only-cost-you-40/
I guess this is a response to the cheap copies of OS X? Though those were never a real competitor to Microsoft, considering you can only install those on Apple machines (and still follow the license agreement anyway)