I do software development on my computer, as well as browsing the Internet, so I'm more safety-conscious than must users. I have taken a number of precautions; what is relavant here is that I have always thought that the typical user's attitude toward the Internet is as risky to his computer as having promiscous sex without condoms is to his body, and for the same reasons.
I use Netscape, and leave the following options turned off:
1. Load images automatically. Instead, I push the Images button when I want them for a specific page, which isn't very often.
2. Java. I NEVER turn it on.
5. I never install optional things for my web browser.
Most of the annoying things on the Internet come from abandoning safe practices like these. That's fine if you only use your computer on the Internet; you can easily wipe it clean and reinstall everything after it gets a fatal infection, can't you.