According to security vendor DriveSentry, about half of downloads claiming to be free versions of Microsoft Windows Vista are in fact malicious Trojan horses. With Vista's consumer launch just days away, discussion boards and peer-to-peer networks are full of offers of "cracked" versions of Windows Vista. The downloaded programs claim to skip Vista's activation process but are in fact malicious key-logging software and spyware. This isn't anything new though, the same deal occurred with Windows XP. Pirated versions of Vista have been in circulation for several months now, and one called "Windows Vista All Versions Activation 21.11.06" has already been identified as a Trojan. It's an effective technique, said John Lynch, vice president of sales and marketing for DriveSentry. "Someone that's stealing the software to begin with is not going to raise a fuss if the software turns out to be malicious."
News source: InfoWorld