http://www.networkworld.com/news/2010/051010-windows-7-compatibility-checker-is.html?hpg1=bn
    
Windows 7 ‘compatibility checker’ is a Trojan
A fake e-mail with the Trojan lifts text from a Microsoft Web site about the real software

Scammers are infecting computers with a Trojan horse program disguised as software that determines whether PCs are compatible
with Windows 7.

The attack was first spotted by BitDefender on Sunday and is not yet
widespread; the antivirus vendor is receiving reports of about three
installs per hour from its users in the U.S. But because the scam is
novel, it could end up infecting a lot of people, according to Catalin
Cosoi, the head of BitDefender’s Online Threats Lab. “This actually
works because of the interest in Windows 7,” he said.