Spybot: Search and Destroy
Spybot - Search & Destroy (often Spybot-S&D) is a Windows malware, spyware and adware removal program. You can download Spybot here.
Using
Updating
Select the "Update" button to get the most up-to-date version of Spybot.
Search & Destroy
This button reveals the "Check for Problems" button, which scans the computer for various adware and spyware.
Immunize
This automatically tweaks some internal settings to block the installation of known spyware (and similar threats) installers. This very useful feature will prevent many malicious programs from ever loading.