I've used many of the main vendor's' security products over the years, more recently trying AVG and Avast! suites, both retail and free versions, some with more stability/upgrade troubles than others.
I found the previous MSE version to be simple to install, and painless to keep up to date due to its tight integration with the built-in Windows Update procedures (with daily or on-demand updates). It interacts seamlessly with the Windows Firewall and other Windows components.
It raised a warning every month or two that was easy to understand and respond to. I think several of the warnings were false positives (I've got heaps of developer tools on my machine, and it's no wonder that the odd executable or two in that lot would appear to MSE to be highly suspect).
There were also one or two warnings that proved to ne real malware - no matter how careful you are, sooner or later some nastie or other is bound to make its way to your system - which MSE appropriately quarantined and subsequently deleted.
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