One of the Microsoft's best kept secrets, though not an intentional one, is the fact that it's quite easy to upgrade a PC from one version of Windows 7 to another.

Computers running Windows 7 have all of the features of the high-end Ultimate edition built in. A feature called Windows Anytime Upgrade lets users buy a code and unlock new features, a process that the software maker says can be done in just 10 minutes. Unfortunately, Microsoft hasn't had much luck making users aware of or interested in such upgrades.

The software maker is hoping to change that with a promotion that starts Sunday. Certain retailers will be offering those buying a new PC the opportunity to buy a discounted upgrade to a higher-end version of Windows 7. In the U.S., there are two offers, though not all retailers will be offering both. Those buying a PC with Windows 7 Starter (the version found on some Netbooks) will be able to go from that version to Windows 7 Home Premium for $49, as compared to $79, while a move from Home Premium to Professional will be sold for $79 as compared to the usual $89.

The offer will run for a limited time, until July 3 in the U.S, Microsoft said in a blog posting.

Full story: c|net