Microsoft Security Essentials

I never thought I'd find myself recommending a product from Microsoft, but Microsoft Security Essentials billed as "The anti-annoying, anti-expensive, anti-virus program" rocks. Free for up to 10 computers this thing lives up to those claims. Since there's no "premium" version unlike almost every other Windows antivirus, there's no need for nagging, or ads. The updates are smooth and require no user intervention, unlike a particular open-source windows av. MSE also provides real-time protection which in some similar products is a premium feature. I really haven't found anything to dislike about this product just yet, and I will certainly be installing it on the computers of everyone for whom I end up providing pro-bono tech support.