The Microsoft Anti-Spyware is actually quite good as well, and free:
http://www.microsoft.com/athome/secu...e/default.mspx
Webroot's stuff is also quite good, you could download their trial:
http://www.webroot.com/consumer/prod...2-HHO_Links-SS
The thing with spyware is one or even two different scanners often aren't enough to catch everything on a really badly infected PC.
The advice with the hijack this and forum post is also good.