I've used the free Spybot Search & Destory for over 10 years now over the lifves of several computers. I've contributed to their work several times and consider that I got value beyond what I have contributed. Spy Bot caught Trojans and invasive toolbars that other subscription software was missing. I use it as a backup plan to Norton. So far this year it has found some tracking cookies and a toolbar (BADu?), but I plan on purchasing the professional product. I'm pretty sure I will still get good value with their purchased product.
The download site shows a Microsoft Certified seal and one other seal I don't recall. In hindsight, they were apparently ripped off.
Even after Norton quarentined this file, it had already spewed enough junk into my computer that it took about 4 hours to clean it all out. I am not an expert at this so I had to hunt down each file.
Thanks to Norton for being on top of this stuff...if it hadn't been quarantined I would probably still be trying to expell these files from my computer.