A while back a staff member asked if I knew of any free antivirus software
This is the software we use in Region 10, they offer free downloads for students and teachers.
Here are a few more;
AVG makes a paid antivirus and also offers a free version.
Microsoft provides "Microsoft Security Essentials" as a free download.
Tools to help remove infections
Malwarebytes is good for scanning and removing malware on your computer
Stinger is a free tool from McAfee that can help remove some infections.
In addition the anti-virus we use in Region 10 (Vexira) has free take home
rights for employees. This allows you to install it on your home computer
but not give it away to non-employees. E-mail me for installation
instructions if you are interested.