I have a subscription service to Norton Antivirus 2004 Professional and I have Ad-Aware SE Personal which is free for private use which detects adware. I also have Spybot Search and Destroy which is again free and scans for spyware. The last program I have for detecting spyware is Spy Sweeper which sadly, costs money for a subscription, $29.95 for one year, $39.95 for two years. I don't remember how much the Norton Antivirus 2004 Professional subscription costed but it scans for adware and malware.

Norton Antivirus 2004 - http://www.norton.com/
Ad-Aware SE Personal - www.lavasoftusa.com/
Spybot Search and Destroy - http://www.safer-networking.org/en/index.html
Spy Sweeper - www.webroot.com/