Windows 7, which is set to reach the end of its mainstream support cycle on 13 January, 2015, now has another deadline looming.

As announced by Microsoft, new PCs pre-installed with Windows 7 Home Basic, Home Premium, and Ultimate editions of the company's popular operating system (OS) will no longer be sold from 31, October 2014.

Retailers can clear-off PC stocks running these Windows 7 versions, but newer stocks will not be delivered to stores from the cut-off date.

On 31 October, 2013, Microsoft stopped selling all retail software versions of the Windows 7 OS (i.e. boxed copies of the OS not pre-installed on a PC - Windows 7 Home Basic, Home Premium, Ultimate, and Professional).

Windows 7 Professional gets a breather

Microsoft has yet to announce a date for the end of sales of the Windows 7 Professional version pre-installed on PCs. Microsoft will provide one year of notice prior to the end of sale date.

This means that users still have plenty of time to buy laptops, desktops, and tablets pre-installed with Windows 7 Professional.

Where to next for Windows users? Windows 8 and Windows 9

With Windows 7 set to soon enter its extended support lifecycle, Microsoft is intent on getting its users to move over to Windows 8, an operating system that has struggled to garner PC users.

Currently, Windows 7 users wanting to upgrade have only Windows 8 to choose; but Microsoft is poised to release Windows 9 by mid-2015, with a 'Technology Preview Beta' due in October 2014.

Apart from Live tiles and Cortana, Windows 9 is also expected to incorporate the 'One-Click Stable Build' feature to let users obtain and install upgrades without having to format their computers each time.

Windows 7 set to enter 'Extended Support' Phase - What is 'extended support'?

Users already happily running the various versions of Windows 7 (and with no inclination to upgrade to Windows 8) need not fret just yet.

Windows 7 mainstream support ends on 13 January, 2015, and extended support ends on 14 January, 2020.

During the period of the 'extended support' scheme security fixes will be provided for free, but non-security hotfix support will have to be purchased within 90 days of mainstream support ending. During this period, Microsoft will also no longer accept design-change requests, new feature requests, and warranty claims.

Beyond the extended support cut-off, users can strike deals with Microsoft (dpeneding on their region) to receive further support, but for the most part users will be left to fend for themselves if they continue to use the old systems. Windows XP is an example of a Microsoft system that has passed its exended support cut-off date on 8 April, 2014.