Microsoft today made available for download a new release of its free anti-virus/anti-malware program for Windows PCs, Microsoft Security Essentials (MSE).

The MSE 4.0 release is available via the Microsoft Download Center and the MSE Web site. (I learned of its availability from a post on Neowin today.) The latest version runs on Windows XP, Windows Vista, and Windows 7.

The 4.0 version has been in beta since late 2011. As ZDNet sister site TechRepublic reported back in December 2011, Microsoft officials said the 4.0 release would include a streamlined interface; a renamed version of the SpyNet service (now slated to be known as Microsoft Active Protection Services); new automatic remediation functionality; and overall improved performance and detection capabilities.

I've asked Microsoft officials if there's anything else worth noting that is part of the new release. Here's the statement from a spokesperson:

This update to Microsoft Security Essentials is part of the standard product update release cycle. This service update contains product enhancements to improve performance and user experience. We have improved on Microsoft Security Essentials' Automatic Remediation, which will automatically quarantine highly harmful threats without prompting the user to take action as well as minor bug fixes in set up, malware remediation and other areas."

I just checked to see what version of MSE I was running on my Windows 7 PC and it was a 2.X release. I'm wondering whether that means Microsoft doesn't push updates of this service to users via Windows Update or whether the most recent release before this one was 2.X.

The aforementioned spokesperson did say, when I asked, that "this version of Microsoft Security Essentials will be made available to existing customers automatically through the Microsoft Update service."

Just a reminder about MSE's origins: MSE was aimed first and foremost at users who either can't or won't pay for antivirus/anti-malware software, with the idea being that more secure Windows PCs mean less security risks for all Windows users. With MSE, there is no registration required, no trials with an expiration date or required renewals. But Microsoft does restrict the MSE download (both the beta and final) to PCs running Genuine Windows (which has been authenticated as non-pirated).