Webroot Spy Sweeper is the only program out there other than Microsoft Antispyware that really has strong real-time protection. Ad-Aware and Spybot both do a great job of cleaning a system up, but neither does a very good job of preventing spyware infestations. With version 4.0, Spy Sweeper also runs correctly on multiple user accounts on Windows XP, even limited users! And unlike Microsoft Antispyware, Spy Sweeper 4.0 can sweep cookies. Cookie detection is also better than in Ad-Aware and other programs since it can differentiate between bad cookies and benign cookies. My only complaint is the lack of spyware protection for alternative browsers like Firefox.