Yesterday in the "SmartScreen Application Reputation in IE9" blog:

    ... 1 out of every 14 programs downloaded is later confirmed as malware.

Coincidentally yesterday was also the first day in years I got infected by malware. I needed some video editing software (more on that in a moment) and one of the tools I downloaded inserted a Firefox redirect trojan. Basically whenever I tried to go to Google, Facebook, Hotmail, or an anti-malware site, it tried to redirect the browser to an ad site. For some reason it failed (hopefully because the target domain has been shut down, disconnected, and melted into a puddle of slag!) but it still stopped me from going where I needed to go.

I installed and ran SUPERAntiSpyware and Malwarebytes' Anti-Malware and was back up in running in a few hours. (Okay not so few because I have a big disk to scan.)

The morale is: be careful out there. Even if a site looks legit, that doesn't mean it is. And even if it is, that doesn't mean their software isn't infected.