I don't know about you but I download a lot of stuff from the Microsoft website and I'm continually being asked to validate my operating system as genuine. The idea is that I'm somehow being protected from ills by running a genuine copy of Windows. I'm not convinced, but here's an idea for Microsoft if someone there is looking for a way to make computing better and safer for everyone - do a silent run of the Microsoft Windows Malicious Software Removal Tool (MSRT) every time someone requests a download.
The MSRT is a small download that scans Windows platforms for infection by some of the most commonly found malware (stuff like Blaster, Sasser, and Mydoom - you can see a full list of malware detected here). The MSRT is pretty basic but it works.
Microsoft releases a new version of the tool on the second Tuesday of every month (Patch Tuesday) but there are plenty of computer users out there who never apply updates so these systems never get scanned (and these systems affect all of us - they're the systems sending out the junk mail and malware). I'd support Microsoft in making a MSRT scan a requirement before downloading non-security updates (and make it an option before downloading security updates) from the Microsoft site. It might not help protect Microsoft's profits, but it sure would help reduce the number of machines out there that are part of botnets under the control of criminals.