Following a four-month beta program, Microsoft Security Essentials (MSE) 2.0 has been released. The new version significantly revamps the heuristic scanning engine, adds Windows Firewall integration as well as network traffic inspection. The update unquestionably makes MSE, which has already become very popular due to its quiet but effective ways, even more of a must-have for Windows users.

MSE has always been very good at finding and removing malware, but it has relied mainly on antimalware definitions. The improved heuristic engine makes it even better at detecting threats; at the same time, we expect the number of false positives to slightly increase as well. The new Windows Firewall integration is a minor improvement: it lets you tweak Microsoft's firewall from inside MSE.

The network inspection feature does exactly what its name implies: inspect traffic as you browse. It uses the Windows Filtering Platform in Windows Vista and Windows 7; Windows XP users won't be able to benefit from this feature. The Windows Filtering Platform allows programs to plug themselves into the networking subsystem and monitor any network traffic, even whatever is allowed through the firewall. MSE also now integrates with Internet Explorer to better protect against Web-based threats by preventing malicious scripts from running. Version 1.0 only detected such scripts when they were written to IE's cache, by which point it could be too late.

MSE is free for home users and free for small businesses with 10 PCs or fewer. For larger enterprises, there's the Forefront suite. Forefront uses the same core anti-malware engine as MSE, and so it's not surprising that Forefront Endpoint Protection 2010 has also hit the RTM milestone at the same time, though it won't be available to volume licensing customers until January 1, 2011.

On the other hand, MSE 2.0 is available now from the Microsoft Download Center. If you already have MSE installed, it should have automatically updated by now, and yes, it probably required a restart.