A lot of PC users are going to see Windows 10 suddenly appear on their machines this week.

Windows 10 has been changed to a ‘recommended’ upgrade – from an optional one.

If your Windows 7 or 8 machine is set to automatically install recommended items (the default setting), it will download several gigabytes of data.

Microsoft says that users still have the choice of whether to upgrade, according to a report in The Register.

Microsoft said in a statement, ‘As we shared in late October on the Windows Blog, we are committed to making it easy for our Windows 7 and Windows 8.1 customers to upgrade to Windows 10.

The files for the upgraded OS will download quietly in the background, and users will have to agree to a dialogue box before the system upgrades.

Microsoft claims that the software is faster than previous versions – and it brings back features including the Start Menu, missing in Windows 8.

Microsoft says, ‘Windows 10 starts up 28% more quickly than Windows 7, resumes faster and comes with more security features than ever.’

Microsoft says that new users will be given the option to revert to their original system within 30 days after installing Windows 10.

The change only affects home customers, not business users.