best antivirus for PC

I do not know why this time my computer often wrong, and the reaction is also particularly slow, let me read a few friends to help me, did not read to what is wrong, but I work every day is to use computer, the computer becomes so is really inconvenient, so I wanted to go out this afternoon to let the computer repair computers to see, when I was about to go out, I saw a colleague, so I put the case to him one said, colleagues open the computer only on a computer installed above a best antivirus for PC, then use the best antivirus for PC anti-virus for a while, my computer just fine, really God. Later, a colleague reminded me like nothing more than to antivirus. The best antivirus for PC too God it.