4uvak: It is not nessicary to start similar topics, As I already Explained with the firewalls, it slows preformence. So you definitly shouldn't have 2 AV programs.
I think it depends how they work. For example I have two, one AVG which is on-access, the other ClamWin isn't. They work fine together because they aren't both on-access, and because there not competing with each other.