Microsoft is widely expected to introduce its Windows 9 operating system at an event in San Francisco next Tuesday and rumors have been flying about what we can expect from the successor to Windows 8.

Now we can add "free upgrades for Windows 8 users" to the mix of speculation in advance of the unveiling of the next-gen software platform code named Threshold.

The source behind the latest rumor? As spotted by BGR on Saturday, Indonesian tech site Detik earlier this week quoted Microsoft Indonesia president Andreas Diantoro as saying that "the Windows 9 upgrade will be available free of charge to all existing Windows 8 users once it's released."

The Detik article is in Indonesian, but BGR gleaned from a translation that once Threshold is released, Windows 8 users "will be able to easily install the Windows 9 update after downloading it from Microsoft."

In fact, the rumor that Redmond could be planning free Windows 9 upgrades has been kicking around for some time, with variants suggesting that legacy Windows XP users may also be gifted free upgrades. If any of these rumors prove solid, what's unclear is what happens to users of other Windows OSes like Vista and Windows 7, BGR noted.

PC Magazine