Microsoft will release a limited public beta version of its Microsoft Security Essentials (MSE)— formerly code-named Morro—tomorrow in the United States, Israel, and Brazil. The anti-malware add-on will work with Windows 7, Windows Vista, and Windows XP, and will be free when the final version is released worldwide by the end of 2009.

"Microsoft Security Essentials is security you can trust," Microsoft anti-malware general manager Alan Packer told me in a briefing earlier this month. "It includes award-winning anti-malware technology with real-time protection. It's easy to get and use, and will be available at no cost directly from Microsoft to all genuine Windows users."

MSE is based on the same anti-malware technology that the company builds into its other products, such as Forefront and Hotmail. And though it will effectively replace the discontinued Windows Live OneCare in the marketplace, it has been upgraded internally since that product to support a dynamic signature service that provides for near real-time signature updates so that users' PCs are always up to date.

MSE is improved over OneCare in other ways, too. Although the software lacks any of the PC-management functionality that Microsoft added to OneCare, MSE is much smaller, lighter, and quicker. And unlike OneCare, it doesn't burden the user with constant, unnecessary notifications.

After the initial MSE public beta release this week, Microsoft will begin rolling out the beta to other locales, beginning with China later next month. The final product will ship in the third quarter of 2009, about the same time as Windows 7.

For more information about the MSE public beta, please refer to the SuperSite for Windows.