Microsoft will kick off a Windows 8 upgrade program for buyers of Windows 7 PCs in early June, according to a report.

But unlike past deals, this one may come with a price tag.

The program will, said CNET yesterday, provide a discounted upgrade to Windows 8 to anyone who purchases a new Windows 7-powered PC between June 2012 and January 2013.

Citing unnamed sources, CNET said that the upgrade offer would let buyers of Windows 7 systems purchase Windows 8 Pro -- the highest-priced edition that will be sold at retail -- for an undisclosed price.

The offer will debut at the same time that Microsoft launches Windows 8 Release Preview, which the company has pegged to the first week of June. The most likely date is June 5, assuming Microsoft follows the same schedule it used in 2009 to deliver Windows 7's release candidate.

Three years ago Microsoft ran a similar program for Vista-to-Windows 7 upgrades, which was itself a repeat of a 2006 deal that promised buyers of Windows XP machines an upgrade to Vista.

Both deals provided the newer operating system for either no cost or for a small fee. Details varied, as computer makers actually fulfilled the offer, with some charging shipping and handling fees while others gave the upgrade to earlier buyers gratis.