I personally use MSE and Windows Firewall and set it up to automatically scan the computer periodically. And let windows update automatically along with security updates.
So I never notice it exists till I want to. As most other programs I used in the past will usually do more than just an update and require a new instal of the program or something else that bugs me a bit. While this one doesn't and it just works. Oh and it's free, so no worries on paying for a subscription or anything of that nature.