Microsoft has officially launched its mobile and tablet-orientated Windows 8 operating system at an event in New York.

The operating system, which is also aimed at PCs, has been designed with an emphasis on touch-screen technology, Windows president Steven Sinofsky told the launch event.

"Windows 8 is a major milestone in the evolution and revolution of computing," said Sinofsky. "In creating Windows 8 we shunned the incremental - we boldly re-imagined Windows."

Microsoft will make Windows 8 generally available on Friday at 12.01am local time worldwide, Sinofsky said.

The operating system will include security features such as Defender, available in Vista as anti-spyware, as a rebadged version of Microsoft Security Essentials anti-virus technology, according to security company Eset.

At a firmware level, Microsoft Secure Boot will require boot loader code that is digitally signed, a feature designed to mitigate BIOS-level rootkits.

A further boot-security process is Microsoft's Early Launch Anti-Malware (ELAM) technology. ELAM allows anti-malware software to be the first non-Microsoft software to run while the operating system is still loading, Eset said on Tuesday.

Possible security issues with Windows 8 could include increased use of social-engineering attacks against users unfamiliar with the operating system, ESET added.

Take-up of Windows 8 is expected to be high over the next two years in the run-up to Microsoft ending XP support in April 2014.