Some number or people, few people I believe could use a PC without any AV at all and yet remain virus-free, but most people could not have that kind of luxury, simply because most people didn't have enough knowledge or using their PC at high risk environment, not because they like that risk, but because "their needs" force them to enter that high risk environment.
When we're talking about knowledge in computing world, you could never have enough, no matter what, technology keep moving on, and if you're not someone who is constantly following it, than you will surely outdated. So I believe, unless your an IT guy or an IT expert, that would place you in the "not enough knowledge" position.
Personally I realize, my position as one of the "not enough knowledge" position, cause even though I read & try to follow up with the technology in computing, still I don't have any background on computer science, just someone who is "force" to use computer in a daily life and force to adapt with it.
So when it come to computer security, I would say most people would be in a vulnerable position, and that few people who laugh on other people because they tried to equip them self the best that they can as the paranoid person would be an arrogant statement. Because we, as most people of the world who use computer didn't know as much as them, there's probably last than 1% of people who is a real computer nerd, even though there is some people who think and believe they are nerd and support the nerd opinion, which would place them as both arrogant and foolish.
I don't mind to be called paranoid person on this matter because I provide my self with the amount of equipment that been suggested on the book, even though it still could not give any guaranty I could be 100% save. The fact is, there's no antivirus software or any security software that could provide 100% protection, that's why no test in the world give 100% score on it's test to any security software vendors.
I decide to stay on the saver side, or you may say the paranoid side, I will continue to use my own personal free security suited, and the combination didn't seems to compromise my PC performance significantly. The free suite which contain :
- Avast Free Antivirus as my real time Antivirus protection
- Outpost Firewall Free, since XP firewall is far from perfect
- Spyware Terminator as the antispyware protection
- ThreatFire as my zero-day threat protector
- SpywareBlaster as the passive immunization protection.
- Sandboxie as virtualization.
- and an on demand scanner such as Malwarebytes (as an anti-malware scanner), A-squared Free & SUPERAntiSpyware