Hehe, if you're using Windows 2000 or XP, let me teach you a trick called "the golden cicada shedding its shell" — and with just this one trick, you can kill all viruses!
If your system is freshly installed (or if you can confirm that your current system is virus-free), then it's perfect. Open the following immediately:
"Start → Programs → Administrative Tools → Computer Management → Local Users and Groups → Users."
First, change the super administrator password to something more than ten characters long. Then create another user, set its password to also be more than ten characters long, and promote it to super administrator status. The purpose of doing this is twofold: if you forget one of the passwords, you still have the option of logging in with the other super administrator password to regain access, preventing you from being locked out of your system. Additionally, hackers on the internet won't be able to remotely gain control of your system by guessing your super administrator password, thus preventing damage. Next, add two more users, for example, named user1 and user2, and specify that they belong to the user group. That completes the preparations. From now on, unless absolutely necessary for system maintenance, don't log in as the super administrator or user2; just use user1 for daily activities.