Regular use of spyware detection tools like Spybot Search & Destroy and Ad-Aware will rid your computer of malicious programs that are silently downloaded when you browse the Web. Spybot's Immunize feature provides extra security by preventing spyware programs from being installed in the first place. To enable the Immunize feature for Windows XP/Vista:

1. Start Spybot Search & Destroy.
2. In the list on the left, click on the Immunize button.
3. In the list at the top, click on the (Plus) + Immunize button.