Chrisg34 :
Avast is the best antivirus, i have also use this in my pc.
There really is no such thing as "the best" for antivirus software. There are certain AVs that are better for various users, yes; however, there really is not one AV that even catches 100% of all viruses currently out there. In fact, there are many types of malware that are produced on a daily basis that no AV will pick up, because they are primarily used for other purposes (think of Stuxnet, but for a number of different purposes). There are actually a number of software engineers who happily give out RATs, trojans, and other types of viruses/malware, openly on a number of web forums. They are specially designed to avoid being detected with the typical methods used by AV software, although they are not intended for a mass release like most viruses that average computer users will get. Just throwing that out there.
Also, Avast is known for being a problematic AV, not catching a number of viruses that many other AV companies will catch, and having problems with false positives/alarms. Not trying to talk anyone out of it, but it definitely is not one of the better AVs; and it definitely could not be considered "the best," if you're basing that title on real world protection.