What is "nurech.b"

Nurech.B is a computer worm that infects computers through MSN Messenger. It inserts a link in the chat window while you are chatting with someone, thus making it look as if your friend sent it and thus exploiting that trust. Once you click on that link, it downloads an .exe file with a name such a "Valentine Card" or "Happy Valentine's Day". Once infected, it spreads through your MSN to your friends and is invisible.