According to ZDNet Australia, if you want your computer to be as disease-free as a virginal Catholic school girl lesbian, you’re better off going with the little guys than Symantec, McAfee or Trend Micro.
The reason’s fairly common sense: it isn’t that these anti-virus programs are bloated and badly programmed (although there is that), it’s because most virus and malware authors test their code against the most popular apps. There’s an 80% miss rate amongst the most popular applications.
Malware authors are getting more and more skilled. One expert in the article claims that the quality of the code these days is worthy of professional software engineers.
If you want to keep your system clean, the prescription has been standard for the last few years: stop using Internet Explorer. Set-up a firewall. Download a free antivirus software package like AVG and have it scan every night. Periodically run a system check for spyware with software like Spybot. Or just buy a Mac already.