vickyk1: Once infected, you dont need to use the messenger or even the PC, the virus automatically sends links to online contacts, these links can be of all sort of crap.

More info here:
http://forum.mess.be/index.php?showtopic=4399

http://answers.yahoo.com/question/index?qid=20090418194738AAISPMl

And you can do a google search to know about the messenger virus and how it works.