As graupma has mentioned, Microsoft Essentials (their stand-alone AV) actively disables Windows Defender.
Both WD and ME are "preset and forget". It is not possible to configure either of them to your tastes and needs. Given that both products are aimed at Microsoft's preferred clients, then you should seriously consider some real protection.
Some on this thread, and many elsewhere, have actively recommended you avoid corporate all-in-one bloatware: Norton/Symantec and MacAfee feature largely in these posts.
To be honest, any stand-alone which offers user configuration will do the job. The reality is that (forgive me if I'm wrong) your system is only at risk from "casual" infection: something that arrives in the email, or a malicious website. Many software companies offer freeware AV, or you can spend some dollars and get their "Pro" versions. Personally, I wouldn't bother. I use Avast! Free, and it works like a charm. I did have to configure it, but then that's why I ditched ME and made sure WD would never rise from the grave.
Now if I had an "at risk" setup, holding sensitive data belonging to other people, then some more depth would indeed be necessary. So much for the risk analysis
I do have to say that one reason for choosing Avast! is their easy-to-use boot scan, which loads a preset scanner before Windows loads. This eliminates the need to make a bootable stick or CD, which can be a hassle.
And to everyone here, there and elsewhere: A Merry New Year, followed by lots more of them!
Gordon.