Using a firewall.
Only downloading programs from Web sites you trust.
Installing anti-spyware protection.
All the above.
Trend Micro PC-cillin
Every 3 months
It lets you secretly read other people's e-mail.
It blocks advertisements from popping up while you surf the Internet.
It performs tasks on your computer without your consent and control.
It performs scheduled tasks on your computer.
I and II
I and III
II and III
III and IV