internet viruses?

Most hackers do their thing anonymously, sometimes even in stealth mode. It's kinda hard to detect these guys (FBI may track them easily though). On the other hand, if you're concerned about your computer's security (sounds like you do), you should try ZoneAlarm Firewall. It has a feature where you would know how many intrusions (probably attacks from hackers) were being made or in this case, blocked by ZoneAlarm throughout your whole internet session.