Microsoft has released Security Essentials 4.0, the latest version of its lightweight, straightforward antivirus package.

The bulk of the changes this time are under the hood. MSE’s “Automatic Remediation” now does a better job of quarantining threats on its own, for instance, no user intervention required. And Microsoft claims scanning performance and malware detection rates have both improved on the previous build.

The program can now also use the Microsoft Active Protection Service (the new name for SpyNet) to automatically report malware to Microsoft, helping the company to create new definitions and more quickly respond to new outbreaks. (Although of course if you’d rather the program didn’t “phone home” at all then you can turn this off entirely.)

A simple interface ensures MSE is extremely easy to use

And there’s the obligatory minor interface tweak or two, all of which help make Microsoft Security Essentials 4.0 just a little easier to use.

In theory, at least, the program should be automatically made available to existing users via Microsoft Update. In which case clicking About Security Essentials (from the Additional Help Options menu) should reveal a Security Essentials and Antimalware Client version of 4.0.1526.0 or greater.

Some people are reporting this hasn’t worked for them, though, and if you’re one of them – or you just want to try out the program for the first time – then Microsoft Security Essentials 4.0 32-bit and 64-bit downloads are available now.