"Two new Bagle worm variants and the worm's original assembler source code were spreading around the Internet on Sunday - a dangerous development, according to security experts".
Just think about it... one moment you are happily downloading illegal warez, the next your beloved machine is downloading a Trojan that effectively enlists that computer into the worm author's Zombie army, which can be used to distribute spam and other malware and to launch DDoS attacks.