Avast , AVG and Avira???

I have the three anti virus above.Can I use them at a same time?

(Real Time Protection)

Avast , AVG and Avira???internet security

NO! Only use one antivirus program at a time. If you wish to supplement it, use ThreatFire.

ie, AVG + ThreatFire.

To uninstall your extra antivirus programs, I would recommend that you use RevoUninstaller.

Avast , AVG and Avira???network security

Why employ three when one can do the job well. In particular if the three conflict with each other. Each one should detect the other and perceive it as an intruder / virus trying to take over your computer. I currently use Iolo Antivirus because I purchased it as a package deal with system mechanic. I had to remove AVG in order to install the Iolo antivirus the program stated that there would likely be conflicts - in some cases their maybe similiar components that may cause conflicts since the programs perform the same role. I am and still remain an AVG fan - when my subcription updates stop for Iolo I am going back to AVG.
AVG
Using more than one antivirus does NOT mean more security. It could actually decrease your level of protection.

Back in the days I used to use Windows, I used Avast. Ever since I started using it, I didn't pick up a single virus; and this was over a period of ~3 years. For Windows, I think that's a superb record.

So yeah, Avast!.
You could, but they may cause conflict. You could have them all on but turn off real time protection on 2. I reccommend avira, i think its better than AVG
yea you can use them at the same time...

will they cause major conflicts in your computer? perhaps

will they probably cause your computer to slow down in terms of connection speed, and overall speed? more then likely

will it give you more security and protection to have all three instead of one? nope

i would recommend AVG partly because it is so damn popular and partly because i have used it for some time and it has guarded me from many a foul worm.