best antivirus for PC

My own computer to install this best antivirus for PC later, and now my computer has reacted a lot faster, the best antivirus for PC Mu is also good. Although I use the computer every day, but, if there is anything wrong with the computer or something, I do not know how to deal with every time there is a problem and I are looking for someone to help me repair, or the repair is out to let others, a few days ago the computer a slight problem then I came over to give me a friend installed a best antivirus for PC, said to be the best antivirus for PC is very good, when nothing more with it, will be good, so almost every day I would go to anti-virus, and now the computer is very good with them stick.