Microsoft VP Jim Allchin recently told a story about Steve Ballmer and it turned out to be a good one. Steve Ballmer was at a wedding reception when the bride's father said that his PC was slowing to a crawl and asked Ballmer to check it out. PAUSE. This is Microsoft CEO Steve Ballmer. Just keep that in mind.
So Ballmer took the PC under his care and the CEO and manager of the Operating System in front of him COULD NOT rid the PC of malware and spyware.
Ok, ok he couldn't do it. Maybe he is just a business man and isn't that techie. Ballmer sent the PC to some of Microsoft's best engineers and they could NOT rid the PC of spyware and malware no matter what they tried. The PC was infected with over 100 pieces of malware: many of which the TOP engineers could not exterminate.
Moral of the Story: If Microsoft's CEO and top engineers can't rid their own OS from malware and spyware then how do you expect the ordinary person to do so?