The only way to keep your computer that secure is to unplug it from the internet, wait months after updates come out, rigorously testing against malware and antivirus engines, then updating... which ends up being a waste in time and computing because most updates are security based. An offline computer is the only safe computer.
Do not get hung up on security to the point of not using the internet. You lose more by not having access. Use common sense, any deal to good to be true is... think before you click. Hover to see links and if it redirects. Use strict permissions in your browser and set your email client to convert all emails to plain text. That is the safest you can be. Update regularly and relax, because most encounter viruses and maleware because of bad intentions (pirating software or movies or songs, xxx surfing and other less reputable net uses).
Regular use will not be your insecurity.... clicking a link in email that comes from fb, which isn't Facebook, about someone accessing your account (which never happened) will be your downfall. Bottom line, THINK BEFORE YOU CLICK (emphasis not yelling).
