Yes I have Norton 360 and I'm running SuperAntiSpyware Free Edition
1) I think Defender is a waste of time and resources. I always disable it.
2) You MUST have an anti virus utility active at all times. Defender is not an av and Essentials, to the best of my knowledge, does include an av. Do you have an av?
3) A much better malware tool than Defender is MalwareBytes
About Microsoft Security EssentialsMicrosoft Security Essentials provides real-time protection for your home PC that guards against viruses, spyware, and other malicious software.
Microsoft Security Essentials is a free* download from Microsoft that is simple to install, easy to use, and always kept up to date so you can be assured your PC is protected by the latest technology. It’s easy to tell if your PC is secure — when you’re green, you’re good. It’s that simple.
Microsoft Security Essentials runs quietly and efficiently in the background so that you are free to use your Windows-based PC the way you want—without interruptions or long computer wait times.
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quote pc adviser;
Microsoft Security Essentials shows much promise. In our tests it was decent at detecting malware, particularly in proactive tests that simulate the handling of new, unknown malware. It took fourth place in our rankings of free antivirus software. The main drawback of the tool, due to launch on September 29, seemed to be its slow scan speed.
One thing we hope Microsoft will improve is Microsoft Security Essentials' relatively poky scan speed. It was the slowest in our on-access scan test, which judges how quickly scans run when you copy, open, or save files. The app's Dynamic Signature Service may account for some of that: When Security Essentials sees a potentially malicious file that doesn't match known malware, it contacts Microsoft servers for additional analysis. The feature likely affords greater protection owing to the use of the latest signatures online, but it may also introduce some delay if Security Essentials has to wait for a response
Microsoft Security Essentials put up no false positives (flagging of benign software), and it got a near-perfect score overall in detecting and cleaning rootkits and malware infections. It detected and disabled every infection, and although it left behind several changes to the Registry and other areas (as every free app did), they couldn't cause further harm
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From Wikipedia
Microsoft Security Essentials (MSE) is a free antivirus software product created by Microsoft that provides protection against different types of malware such as computer virus, spyware, rootkits and trojan horses for Windows XP (x86[4]), Windows Vista, and Windows 7 (both x86 and x64).[4][5] Microsoft Security Essentials replaces Windows Live OneCare, a commercial subscription-based antivirus service and the free Windows Defender, which only protected users from adware and spyware.[6] Unlike Microsoft Forefront family of enterprise-oriented security products, Microsoft Security Essentials is geared for consumer use.
