
iGetcha.org is a suggested opensource and free software directory for the technological sustainability of nonprofits. It's also a simple, non-techie shortlist to assist organizations with a SOHO.
AVG AntiVirus Free Edition is a great antivirus software for your computer. When Google Chrome OS and other open source operating systems start to have a greater impact on the market, and when nonprofits start to see the value of Ubuntu ;) they won't have to worry about viruses. But in the meantime for your windows based computing, AVG has proven to be reliable. Remember that AVG is for private, non-commercial, single computer use. But again, a lot of us working at nonprofits use our own computer in our social initiatives.
Keep in mind, you may want to search for an earlier version of AVG since the newer versions are loaded with ads.