Generally speaking, a safety-conscious web surfer isn’t likely to run into malicious software if they follow best practices for online activity. Which is don’t visit sites that are on the edge of legality, for instance sites to do with
- video game cheats
- illegal downloads of music and videos
- gimmicky free toolbars and emoticons
Steer clear of those and you may well never need your antivirus however you should install one all the same.