1. Get google's popup blocker for IE from google.
2. Download and install Spybot Search and Destroy or Adaware.
3. Disable the computer's messenger service
4. Install a good antivirus utility such as norton, mcafee, avast, avg.
5. Download and install an email antispam utility such as spampal
6. remove P2P software such as Kazaa
7. Configure filtering rules in your email client
8. ...