speaking from experience, Spybot and Ad-Aware both pale in comparison to Spy Sweeper. i used to have both programs, fully updated and everything... and according to them my computer was clean. i get Spy Sweeper, and it finds 98 spyware objects that neither one of those programs found. i can't find the site right now, but there was a reputable computer site that listed the top 10 rated spyware removal programs and Spy Sweeper was number 1, while spybot and ad-aware were both towards the bottom end. even though it's not freeware, all you need is a serial number to make it fully registered, and those aren't hard to find.