First reminder, your system are fine if you never open your system to outsider. Always think that your computer are just a simple sealed box, when you didnt open the seal and the cover, your system will be just fine. But no one can do that because we still need internet, usb Flashdisk, external harddisk, etc. Second answer, using Antivirus...YES, but have you ever heard even someone used antivirus still can be infected by virus and malware? Then how an we protect our system? All you must do is read more and learn more. Read, mean you need to read carefully when some emails or software were trying to be installed after you browse the internet. Or, learn, learn more from anything or anyone have more experiences than you. Decide carefully when you want to do something to your computer system.