best antivirus for PC

My machine because I particularly slow reaction are not used before, and all day on the phone with my brother play to play, but sometimes my brother to go to the computer office would not let me play, every time this time I feel bad to say my brother hurt my computer is not willing to let me play, that day I came home to find my hand notebook actually placed above the table, I was still thinking about who to me this useless machine son and out of it, ready to back the cabinet when I heard my brother say he helped me to loom somehow does, but also installed inside the best antivirus for PC, then do not understand what is the best antivirus for PC thing, because I can not remember these professional terms, but my brother said somehow sure that you can play, I turned on the computer, oh, my machine is really good, now the reaction rate, but Bang Bang .