Initially my laptop came with pre-installed McAffee, but it was only for a trial version and not for the whole year. So instead that I just buy, I searched for the better ones that I can buy. I ended up with Bitdefender. I am not sure if it were the best around, but I am very happy with it. It doesn't cause my laptop to slow down unlike the rest of the antiviruses that I've tried. And it has been really effective in protecting my laptop from viruses I might highly get from torrenting and other free softwares on the internet and documents, things I might get from file sharing from and to people I don't even know if I could trust.