You could try Ad-Aware 2007 7.0.2.3 that you can download from;
http://www.download.com/3000-2144-10045910.html
There is also Spybot - Search and Destroy from;
http://safer-networking.org/en/
you could also look at the Avast site on;
http://www.vnunet.com/vnunet/downloa...t-home-edition
Be careful where you download from though, there are some very plausible "lookalikes" out there.
Paul.