False positives

[Steve]

But you wouldn't want to run  Windows as a vm client without AV either.

[armadillo]

The problem is really you are meant to use one AV, its that simple, the hooks they put in could mean you end up with less protection nas they can cancel each other out, or worse, saw MSE finds a baddy then Avast will see MSE as a threat and try to delete what MSE has tried to deal with thus causing hell as it may take down MSE which in turn will fight back, running two AV's in my opinion is just pointless, one  plus a program like prevx and/or an on demand scanner is the best option. Anywhere you go on the net they generally say never run two AV's its a ticking time bomb, and as I siad, you may end up with less protection than you think, less is more sometimes. 

Very well put. People with two AV's may not be inconvenienced at all until some virus or trojan causes one AV to block the other one and give a free pass to the malware.

[pctech]

But you wouldn't want to run  Windows as a vm client without AV either.

Quite Steve but I was just pointing out that it does not offer double the protection.