Antivirus

You can download any antivirus you want. i like avast, but you are free to choose any. Just google them.

http://www.avast.com/free-antivirus-download

Microsoft Security Essentials is not bad either and it updates within windows update, kind of a nice little bonus for ease of usage:
http://www.microsoft.com/en-us/download/details.aspx?id...