Great post, Spybot Search and destroy will also let you lock your hosts file so it can't be hijacked.
Another couple of links
<a href="http://www.javacoolsoftware.com/sbdownload.html">Spywareblaster</a>
will prevent spyware from being installed.
<a href="http://www.grisoft.com/us/us_avg_index.php">AVG Antivirus</a>
look on the page for the free personal download