You can get the free version of Spyware Doctor by downloading the Google pack here:
http://pack.google.com/intl/en/pack_installer.html?hl=en
After you download and install Spyware Doctor, you can uninstall the Google pack.
I also use the free version of Adaware:
http://www.lavasoft.com/products/ad_aware_free.php
And SpyBot Search and Destroy:
http://www.safer-networking.org/en/download/index.html
Hope this helps you...
