Update: Windows 9 is now known as Windows 10. Want to know more about when you can get your hands on it? Check out our in-depth Windows 10 release date page
Windows 7 users may be able to upgrade to Windows 9 for "something in the region of $30" according to popular Russian Windows "leaker", Wzor.
That's just under £20, or AU$35. Windows 8.1 users are likely to get it for free, something that has been confirmed by our own sources.
Windows 7 was unveiled nearly five years ago and is the preferred operating system for business and enterprise users but has come to its end-of-life with Microsoft retiring it from sales channel at the end of next month.
It is still by far the most popular Windows OS with more than half of the total desktop OS marketshare according to Netmarketshare, accounting for more units than all other Windows versions put together.
What's interesting is that computers running Windows 7 are expected to be able to run Windows 9 - and it's just as well.
Indeed, I expect Windows Vista PCs to be able to run Windows 9 especially as Windows 8.1 is able to run on something like the Toshiba Encore 2 tablet (with a slowish Atom processor, 1GB of RAM, 16GB onboard storage and a WSVGA display).
Windows 9 is expected to be revealed later today in an event in San Francisco with a special emphasis on business and enterprise.