First Look: Microsoft Security Essentials offers free and non-intrusive protection against malware
Microsoft's latest anti-malware application uses the same engine as OneCare, but is smaller, faster and more efficient than its predecessorFollow @infoworld
Most of the time, you'll only know that Microsoft Security Essentials is running because you see its icon in the System Tray. Other than that, it leaves you alone unless it finds a problem. It uses very little RAM or system resources, and I noticed no performance hit on my machine when it ran, except when it performed a scan. When it started the scan, my PC slowed down for the first several minutes of the scan, but then ran fine with the scan working in the background.
Scans and updates are scheduled to run when your PC is idle, although you can run a scan manually. They are given a low priority by the operating system, further reducing their impact on your PC. In addition, CPU throttling is used to ensure that the software doesn't use more than 50% of your CPU.
When Security Essentials finds an infection on your system, you can have it immediately take action against the threat, or you can click Show Details, at which point you'll be shown as much information as the software has about the threat.
When you lick on the Clean Computer option, Security Essentials will either delete the file or quarantine it, depending on the nature of the threat.
Most of the time, that's all the interaction you'll have with Security Essentials -- there's very little need to open the program for any other reason. However, if you do open it to, for example, customize its actions in some way, you'll find a very simple interface that to a certain extent mimics the look of Windows Defender.
There are four tabs --- Home, Update, History and Settings. Home shows you the status of the software and your system and lets you perform a scan; Update shows you the status of definition updates and lets you update them manually; History shows you a history of the actions the software has taken.
Settings lets you change most aspects of how the program works, including when to perform scans, the type of scan to perform (Quick or Full), what actions to take when an infection is detected and the ability to exclude files, locations and processes from scans. There's actually little reason to change any of the defaults, although it's nice to know you can.
When customizing, keep in mind that a Full scan takes significantly longer than a Quick scan. On my system a Quick scan took under ten minutes; a Full scan took more than an hour.
There are anti-malware applications that offer far more customization than does Microsoft Security Essentials. Avast!, for example, lets you finely tune the sensitivity of its scans, so that you can make them more or less aggressive; you can't do that with Security Essentials. Most people won't miss it, but security tweakers may not be satisfied with the level of customization available.
How safe does it keep you?
Until Security Essentials is put through its paces by anti-virus labs, there's no definitive way to know how it stacks up against other applications. However, it shares the same engine and signatures as other Microsoft anti-malware products, including OneCare, the enterprise-focused Forefront and the monthly Microsoft Malicious Software Removal Tool. Therefore, looking at how OneCare compares should give some kind of guidance.