I recommend this antivirus as it has repeatedly won many awards for being a quality product and is totally free. There are no ads, spyware or malware from installing the program. AVG Anti-Virus Free Edition may only be used on one computer for personal use
When you down load the executable file from the link below, it asks if you want the basic or comprehensive install. Choose Basic and the program then downloads the latest files from the AVG servers and installs the program. The comprehensive has a fee tied to it and you get more features which you do not necessarily need depending on what your PC habits are. About 100 megabytes are downloaded by the AVG Download Manager.