[q]As seen in mIRC
* Topic is 'www.eyesonff.com - That's you! | http://forums.eyesonff.com/showthread.php?t=47136 - The June 2004 Ciddies are now on! | If you're running Windows, please run a virus scan, you may be infected with W32/Netsky.P@mm. Thanks.'[/q]
[q]As seen in Java chat
*** Topic is www.eyesonff.com - That's you! | http://forums.eyesonff.com/showthread.php?t=47136 - The June 2004 Ciddies are now on! | If you're running Windows, please run a virus scan, you may be infected with W32/Netsky.P@mm. Thanks. [/q]
As you see, it says topic, and is a general warning, so you probably misread

The virus in question doesn't infect people over chat, but through email and P2P - the reason it's in the chat topic is because of the forged addresses used by the people with the virus match hostmasks of people in chat rather than real email addresses, so it's almost certain the people infected also visit this chat room and probably have logging enabled.