The simplest and most appropriate way to stop security threats, for most people, is to prevent them. The method which should be (but, sadly, isn't at times) idiot-proof is to just use a program.
The most important program you'll need, arguably, is an anti-virus program. This isn't as difficult as some people think, and it isn't as easy as others think. Many people choose not to use anti-virus software because they make the false assumption that it will be expensive or complicated. On the other hand, other people will pick some of the worst anti-virus programs out there for various reasons, such as seeing it on a TV commercial.
For those who are worried about something being too expensive or too complicated, get AVG Free Edition. It's one of the best antivirus programs out there and is friendly to both the computer novice and security expert.
Use a router for improved security - How much?
For those with anti-virus protection already, you might need to make some changes. For starters, if you have two or more anti-virus programs installed on one computer, remove one or both of them. Having multiple anti-virus program can create a number of conflicts and ultimately is more likely to create more problems than solve. Aside from that, some anti-virus programs hog your system resources and slow your computer down immensely. The first that comes to mind is McAfee and the second is the "personal" or "home" editions of Norton Antivirus and Norton Internet Security. The latter in particular is known to cause more problems than it solves. Literally hundreds of users over the last two years have come into the TweakTown Forums complaining of problems eventually proven to be caused by Norton Internet Security. In any case, many commercial anti-virus suites, including the ones I mentioned, use large amounts of RAM and processing power and ought to be replaced.
My personal favorite from experience is Symantec Antivirus Corporate Edition. Although the only theoretical difference between it and Norton should be certain functionality in corporate networks, it seems to work much better than the "home" versions of Symantec products and uses much less resources.
Based on what I've seen in forums and real life, there are a number of other products that get the job done pretty well.
- Kaspersky seems to be work well and is popular due to its performance in detection rate tests.
- Panda also seems to be decent and I rarely see infected systems using it.
- PC-Cillin seems okay and performs well in tests, though I must admit I've seen many more machines using PC-Cillin get infected than I have most of the others.
- ClamWin is one of the more interesting free ones. It has an extremely effective scanner, however no real-time scanner. This makes it next to useless for the average user, and ineffective in comparison with real-time anti-virus programs.
- Free Online Scanners
In addition to the actual programs, you can easily use an online scanner. This is a great thing to do because it gives you multiple sources, which increases the chances of finding a virus. Many popular antivirus software companies provide a free online scan that is equivalent to the program itself. A couple examples include Symantec and Kaspersky.
Before I move on, I should mention that these recommendations are all based on my experiences online and with friends, family, and customers in real life. I have chosen to ignore the plethora of anti-virus comparisons that exist on sites such as AV-Test.org. The vast majority of these tests don't measure anything besides detection rate, and even the ones that do don't make up for human experience.