Avoiding viruses is relatively easy. All you need to do is get a decent scanner, you don't need anything insane, just something that updates itself frequently. When you browse the internet, do not click any ads, ever. Those game ads? Don't loving click them. There are sites that actively upload stuff onto your system even when you're idling though. For these cases, the only way to protect your system is simply not to visit them, or emulate a second system and use that second system to view the sites. The emulation will take the blow, and you could easily reformat it whenever it implodes onto itself under the mass of a billion trojans.
