I tried to install 2 anti virus software (both Mcafee and Norton)on the
same machine, but it seems didn't work. Can 2 anti-virus software both
running at the same time? Why?
Similarly, can 2 different internet security software enable together?
Please advise. thanks!!
Yes, but only if ONE and only one of the real-time scanners (aka on-access
scanner) is enabled. However, since only one will have its on-access
scanner running, that means you would need to manually run a scan using the
other program (and, again, running only the AV scan from one program at a
time). In that case, there probably isn't a need to install both. Just use
the online scanning provided at their web site (it downloads an ActiveX
control to run as a client to download the signatures and then scan your
computer). The online scanner won't fix or quarantine any found viruses but
it serves as a second opinion. Then if you find the online scanner finds
something that your local AV program does not, you can choose what to do at
that time, like disabling the local AV program's on-access scanner and
installing the other AV software.
Most times, there is no point in installing more than one anti-virus program
unless, of course, you choose to install some very crappy AV programs
regarding their coverage. Of the two, Norton's AV has higher coverage so
use its scanner. As far as impacting your system, my experience has shown
that Norton and McAfee impact performance equally (and why I went with CA's
EzAntivirus which has minimal performance impact).
For comparisons of coverage between some AV products, see:
http://www.av-comparatives.org/
Also remember that these are bandaid software. Ultimately it is the user
that decides on the level of security. So your habits (in what you
download, what you run, and how you configure your AV program and response
to it) decides how safe is your host.