One of the offers is directed at consumers who buy new Windows 7 PCs between June 2 and Jan. 31 next year. Available in 131 markets, this offer lets these customers upgrade to Windows 8 Pro for $14.99.

Microsoft hasn't disclosed retail prices for shrink-wrapped, standalone versions of Windows 8, but the current equivalent to Windows 8 Pro, Windows 7 Professional, is $199.99.

Windows 7 editions that qualify for this offer are Home Basic, Home Premium, Professional and Ultimate. It doesn't cover Windows 7 Starter, the most basic version for consumers, nor Windows 7 Enterprise, designed for workplace PCs.

Consumers who qualify don't necessarily have to install the Windows 8 Pro upgrade on the Windows 7 PC they bought during the offer period. They could install the OS on an older PC running Windows XP, for example.

The other offer, announced this week, is for people who bought their Windows PC prior to June 2 and are running Windows XP, Windows Vista or Windows 7. They will be able to upgrade to Windows 8 Pro via download for $39.99 or by purchasing a DVD at a retail store for $69.99. The offer ends Jan. 31 and, like the other upgrade deal, is available in 131 markets.