Microsoft plans to release a beta of its new free computer security program this week and is on track to launch a finished product in the US autumn.

Dubbed Microsoft Security Essentials, it is designed to find and kill malicious software, taking on commercial products from the likes of Symantec and McAfee.

Once the PC security software is installed, Microsoft promises to download updated lists of identified malware daily, but says it will keep a low profile unless it detects dangerous software.

While Security Essentials will compete with rival subscription programs, Microsoft says it isn't going after customers ­ instead, the goal is to improve security overall by getting people who don't have current antivirus software to protect their PCs.