Microsoft is planning to strengthen its Windows AntiSpyware software to protect against wider threats and is re-branding the product as Windows Defender.
Microsoft already bundles a firewall in Windows XP, is planning to launch security software services for both consumers and enterprises, and will launch the Internet Explorer 7 browser with improved security next year.
Windows AntiSpyware has been available as a free beta to users since the beginning of the year.
A new version with the Windows Defender name is planned for users of the forthcoming Windows Vista operating system next year and for Windows XP users.
The upgraded version will detect rootkits, keystroke loggers and other threats, said Microsoft.
The addition of rootkit protection means Windows Defender will be able to detect and remove hacker tools on user machines that are designed to go undetected by security software. Rootkits are used by hackers to control a computer after an initial attack.
The upgraded Windows Defender could be first available to developers who receive a copy of the Windows Vista Community Technology Preview release expected before the end of the year.
Microsoft had planned to deliver Beta 2 of Windows Defender to existing Windows users by the end of the year, but that could now be delayed.