Microsoft has taken the wraps off of its successor to the soon to be discontinued Windows Live OneCare, announcing today that Microsoft Security Essentials (MSE), a free to download “superset” of Windows Defender will become available on June 23.  Ed Bott and Mary Jo Foley at ZDNet have details, but here are some of the highlights:

• First, the company line on what the new software entails:
• To address consumer demand for quality anti-malware protection that’s easy to get and doesn’t slow down system performance, Microsoft Security Essentials has been designed as a no-cost anti-malware solution that provides consumers with quality protection from threats including viruses, spyware, rootkits and trojans. It will be offered directly from Microsoft and has been designed to be hassle-free and is focused on delivering quality protection that’s easy to use.
• MSE will be available for download starting at 9am PDT on Tuesday June 23rd in the US, Brazil, and Israel from http://www.microsoft.com/security_essentials 
• If those sound like a somewhat random choice of countries, well a team in Israel worked on MSE, and Brazil apparently has lots of unprotected Windows machines in use.
• China will also be an early target market for MSE, with a version in Simplified Chinese expected soon.
• Unlike Windows Live OneCare, MSE will not require a Windows Live ID, or any personal information.  It will however, require WGA validation
• Microsoft is saying that MSE will ship “before the end of the year”.

Windows Live OneCare for a time fared poorly in independent tests, but Ed Bott notes that the latest versions of OneCare have been doing much better:

A new study (May 2009) by the independent AV-Comparatives group gave Microsoft OneCare (which shares the same engine and signatures as MSE) its highest (Advanced+) rating. Only 3 of the 16 products in the test earned that rating. Microsoft’s technology scored second in the accuracy ratings, behind AVIRA but ahead of AVG, Symantec, McAfee, and a dozen other products. And on the crucial measure of delivering the fewest false positives, Microsoft stood far ahead of the pack, delivering the fewest false positives of any program tested.

However, and probably at least partly because of its poor showing in the AV-Comparatives tests, Windows Live OneCare was never a big seller.  One advantage to free anti-malware solutions is that they provide a large sample set across the install base, something that OneCare wasn’t delivering and MSE may provide.  Gathering info on a large sample base of malware will not only help to improve MSE, but Microsoft’s enterprise level ForeFront offerings, as well.