The latest (November 2005) edition of the UK magazine Personal Computer World http://www.pcw.co.uk
has a review of anti-spyware. Very briefly:
Two main recommendations -
Microsoft Antispyware Beta http://www.microsoft.com/uk
Still a beta, but ore successful than most, and worth the free download
PCTools Spyware Doctor http://www.pctools.com
Good performance, informative results, free: PCW said there was little reason to upgrade from the free version (to paid-for support). You need free registration for real time monitoring.
Spybot Search and Destroy http://www.spybot.info
Free, quick, useful information but doesn't fix everything
They thought Lavasoft Adaware disappointing for a well-known package. 8 others included in the review.