multiple antivirus software on one pc

It is not a good idea to run two different AntiVirus programs at once, because of not only the conflict, but one could confuse another..

Oh! thankyou. But can I run different ones on different machines on the same network

Yes, and that actually might be a good idea. You can use one to cross-check another; if a virus is caught on one--but not the other, you would know that one virus checker was weak or not up-to-date. It would be slightly more maintenance (keeping 'em straight), but the network would be more secure as a result.

If the PCs on the network are similarly provisioned, it would also allow comparisons as to effectiveness and resource usage between programs.

Once in a while it is good to run the online antivirus. Trendmicro housecall is good enough.

you can run 2 different antivirus ( i am) it all depends on the programs, if you are installing one and it detect the other and advised you to remove it, it would not be a good idea to continue with the installation UNLESS you allow the new install to remove the old Av that was there already.

Personally i have run Mcafee Enterprise and Norton Corporate NEVER had a conflict. Presently i am running MCafee Enterprices with AVG Free and spyware terminator with Clamshield..no
problems
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JUST a personal note ther is no one completed Antivirus program that will detect and proteect you for EVERY SINGLE instances of virus, trojan, malware and spyware. there were the online scanner comes in use from each site once per week

I use, Norts IS 2007 (although i hate the damn thing), AVG free, Spybot S&D and Comodo firewall, and no conflicts.

Question....why would you want 2 antivirus's programs on 1 computer? Wouldn't it cause a lot of competition for CPU %

Not CPU time, but RAM would get used a lot. CPU would get drained however if you ran a scan with them at the same time. Otherwise with normal running of your computer your RAM would get used up.

RAM - CPU Same thing (HA HA)


Seriously though sammy...

If I were you.. I would just one..I would probably get a Software Suite...like Norton Internet Security...

I would also use Windows Defender...

Just a suggestion