Microsoft has officially announced pricing details for the next version of its desktop operating system (OS), Windows 8.1, which will become available on Oct. 18.

Users who are currently running Windows 8 on their devices will receive the update for free just by downloading it from the Windows Store. Meanwhile, those running older versions of Windows and looking to upgrade to the latest Windows 8.1 will be able to buy the new OS either as a download from the Windows website or from a physical store, on DVD.

According to Microsoft's announcement, Windows 8.1 will sport an estimated retail price of $119.99 and Windows 8.1 Pro will cost $199.99. No special upgrade pricing was mentioned.

The company further detailed that it will offer "full version software" both at retail stores and online for download. Unlike with Windows 8, users will not have to run a previous version of Windows in order to install the new Windows 8.1. This means that users will be able to run the new OS in Virtual Machine (VM) environments, build their own PCs, or install Windows 8.1 more easily on a second hard drive partition.

There is, however, one trick. Users running the older Windows 7 will be able to upgrade to the new OS, but they will only be allowed to retain their own files. All desktop apps, including Microsoft Office, will have to be reinstalled. Meanwhile, upgrading from Windows XP and Vista is not supported, which means that users of these OS versions will have to do a clean install of Windows 8.1.

"Windows 8.1 is not designed for installation on devices running Windows XP or Windows Vista. Although not designed or recommended for devices running Windows XP or Windows Vista, consumers still wanting to upgrade from Windows XP or Windows Vista should buy the retail DVD instead of using the download and boot from the DVD to do a clean install of Windows 8.1. Note: files, settings and programs will not transfer - Consumers will need to back up their files and settings, perform clean installation, and then reinstall their files, settings and programs," explains Microsoft.

Lastly, the company further notes that users who buy a device with Windows 8.1 pre-installed will be able to upgrade to the Windows 8.1 Pro Pack for $99.99. Windows Pro users, meanwhile, will be able to purchase Windows Media Center for just $9.99.