Is AVG Free compatible with Microsoft Security Essentials?

(I am running on Windows 7 64-bit.) For a long time, I was just running AVG free, but then my computer teacher said that I need to run both AVG and Microsoft Security Essentials. Do they both do the same thing? I want to know if I can get rid of one of them (Security Essentials) because they are taking up RAM.
11 answers 11