Anytime you add an AV into the picture you're going to get some performance degradation. Add two and you're asking for trouble.
However....From what I've gathered from various posts and personal experience, MSE seems to "Play well" with most AV's. It is one of the rare programs that allows you to run it in conjunction with another AV without causing massive problems
(MSE may cause problem with some AV's, but I haven't heard any mention of it yet)
So it's your choice. You can't be too safe when your on the Wild Wild Web. Not one AV catches them all.
using 2 A/V´s CAN cause trouble, that´s correct, but it depends on which 2 you use...
some A/V´s work together with others.
fx. Avast 5 was DESIGNED to be able to run together with MSE.
so that´s a really good combination, as Avast has some "extra" protection.
a-squared (a2) which is now renamed to Emsisoft Anti Malware (EAM)
also works very well together with (almost) all other A/V´s.
but, you might have to change the settings for the "File Guard"...
i have used a2 as my only "realtime-A/V" for months, and Avast, MSE & MBAM on demand,
just to see if a2 had missed something, but none of them has ever detected anything.
when MSE v2-beta was released i decided to test using EAM & MSE together, and i haven´t noticed any (real) problems.
although a few times i have noticed fx. Firefox "not responding", but that sometimes happens also when i use only EAM.
i have turned off MSE temporarily a few times to see if i notice any difference in performance etc,
a few weeks ago i also added exceptions for each other in both of them, just to see if it would change anything.
NO antivirus-program can detect everything, THAT is in my opinion one VERY good reason to use 2 A/V´s.
if you use the right combination and you don´t have any problems, why not ?
