Key strength and security mechanisms are also moot (of no consequence or use) if your computer is infected with malware (virus, trojan, or some other program) that copies your information. Running antivirus software is a good first step, though like flu shots, antivirus software won’t always be able to block the latest threats. I got a flu shot this year which protected from H1N1 and a few other variants of the HxNy flu virus. If there is a new variant of the flu that wasn’t included in the shot, then I am relatively unprotected from it. Antivirus software works the same way. There are researchers constantly looking at how new viruses operate and updating the virus definitions that antivirus software uses to catch viruses, though new malware is being used from minutes to months before researchers are able to identify it well enough to add the right information to their virus definitions.
There are a lot of good practices to follow in order to avoid getting malware, though none are fool proof and only constant vigilance can give you anything close to a level of security that I would consider acceptable. As I’ve learned personally, no matter how many times I tell my grandfather what to do (and/or what not to do), I still have to clean out his laptop once a month. In his case, he uses his laptop to read news, to look at photos of his grand and great grand children, and to send emails. There’s nothing critical or private that he keeps, so the impact to him is minimal and cleaning things up once a month is sufficient. Most people are not like my grandfather, and regular maintenance is more likely to be needed.
Running a scan with your anti-malware (antivirus) program every night (which can be done automatically if you leave your computer on) is a good first step. Making sure that your program is up to date is critical, as you won’t be able to detect very new threats unless it is up to date. Using a firewall on your computer and on your network can prevent a lot of self-propagating malware from coming in. Tools that look for spyware (such as SpyBot – which I used to use back in the days when I had a computer running Windows) can also be set to scan every evening. There are tools that prevent many of the activities that malware uses to infect your system – such as the Enhanced Mitigation Experience Toolkit from Microsoft. Finally keeping your system and software up to date is likely one of the most critical tasks you can perform to assure you stay uninfected. That doesn’t just apply to your operating system, but to other software installed such as Java, Flash, other browser plugins, and any software you have that you use regularly.
Please note that it’s been a few years since I’ve used a Windows desktop, so don’t blindly run and install software and tools without understanding what they do. There are a lot of good resources online for each type (and often good forums for a specific tool) where you can ask questions and learn about what is best for you.