although coputer security is relatively complex, and many problems are created because of lack of knowledge - most of what described in the article is because of other problems.
you can protect your computer relatively easily from most viruses and trojans, but you'll have to avoid also functinality most people do wan't - like downloading programs from the internet.
it's like a lock on your door - if you install one you're preety secure. but if you let people you don't know get inside, the lock wouldn't help.
another major issue is that computer security can do many things to protect you, but once you're hit theres not always what to do.
to sum up - if security is a major issue for you, and you're willing to invest some time, and avoid some features that are known security holes, you can protect your system.