Those who shell out for a Windows 7 PC in the coming months will receive a discounted upgrade to Windows 8 Pro for just $14.99, according to sources speaking to Paul Thurrott.

The deal could start as early as the first week in June at around the same time as the company gears up for its final preview of the next version of Windows.

The paid upgrade will apply to any new PC buyer with Windows 7 Home Basic or higher installed.

CNET's Mary Jo Foley first reported Microsoft's ongoing commitment to providing PC buyers with promotions during the run-off period to its older operating systems to help lock-in new and existing customers.

Microsoft normally offers free upgrade packages to older editions of Windows that correspond to newer versions: Windows Vista Home Premium users would be given a free ticket to Windows 7 Home Premium if a PC was bought in the months running up to Windows 7's release, for example.

But Microsoft has thrown a spanner in the works by offering only two versions of Windows 8.

The two consumer versions are aptly named Windows 8, and Windows 8 Pro. There are two more editions: Windows 8 for enterprise, though its final name has not yet been announced, and Windows RT, a tablet version designed for ARM-powered tablets.

As Thurrott notes, the Windows 8 Release Preview -- the final glimpse of the forthcoming operating system before its expected October launch -- is set for the first week of June. Available for download only, it will allow consumers and enterprises alike to prepare for the changes.

Microsoft's choice of naming Windows 8 Pro suggests a small- to medium-sized business angle. Unfortunately, it's not quite the case. Microsoft has already taken a lot of heat from customers after it said the entry-level Windows 8 version would not come equipped with Windows Media Center. It also rejects more high-end features such as encryption reserved for Windows 8 Pro users.

But who knows: with the back-to-school season starting soon, students and academics may still be given a free pass.

Microsoft was unavailable for comment or confirmation at the time of writing.

This item first appeared on ZDNet's Between the Lines blog under the headline "Windows 8 Pro upgrade for new PC buyers set at $14.99."