What gamble? Microsoft has a lot riding on Windows 8.

Internet Explorer 9 only . Its successor--Internet Explorer 10--will only work with Windows 7 and Windows 8. The next generation of the Microsoft Office productivity suite is also . PCs that aren't running Windows 7 or Windows 8 are being left in the dust by Microsoft.

Microsoft has been uncharacteristically brazen about drawing these lines in the sand in recent years. The and Microsoft Office (and Windows itself) is tied directly to the success or failure of Windows 8. Now, it is putting its proverbial money where its mouth is, and doubling down with the discounted Windows 8. Making is a compelling offer.

If you use Windows--and you're still using Windows XP or Vista--Microsoft is ready to call your bluff. You're welcome to reject the bargain upgrade to Windows 8 and keep your legacy operating system. After all, it's working just fine so you don't need to upgrade, right? But, you'll be on the wrong side of Microsoft's line in the sand, and you will probably find both support and sympathy lacking when issues arise.

Many users could care less about Internet Explorer 9 or 10. Chrome, Firefox, and a plethora of other options work just fine. There are also businesses and consumers still happily using Office 2010 or even Office 2003, and they're not interested in switching to Office 2013 any time soon. But, the $40 price tag on Windows 8 may still be enough to convince people to make the switch--just to hedge their bets and leave their options open.