If you are a regular computer user, you most likely have been impacted by a computer virus and/or computer failure. So what should you be doing to prevent that? The two things that will help the most are keeping your computer updated and backing your computer up.
Backup is the most troubling for me personally on desktop machines. On computers I manage at work, we use Acronis imaging software, and I am partial to that. Of course, that software isn't free. I now use cloud services like Google Drive and Dropbox for my personal any docs and spreadsheets I utilize outside of work, but that leaves a gaping hole for other types of data that doesn't easily fit in free cloud services. The things I worry about are Pictures, Music, and eBooks. For these, I manually back them up periodically, but even I have gotten burned on not remembering to do that often enough.
For software updates, there is a slightly better story. My recommendations are mutli-pronged:
Make sure you have Windows automatic updates enabled to install new updates when needed. Also that Microsoft Updates are checked, to update any other Microsoft products you are using.
The other major component is Ninite.com. Ninite allows you to select various programs and do a single silent install for all of them. While that is pretty cool by itself, it is even cooler for updates because you just keep the installer you create and every couple of weeks doubleclick on it, it will then install any updates for those pieces of software.
The Windows Update/Ninite combination will take care of about 90+% of software updates that the normal person needs to run.