Ok, he can still disable the Messenger Service in Win2K.
The instructions are pretty much the same, they're here:
http://www.microsoft.com/windows2000...s/msgrspam.asp
There's some nice screen shots there as well.
He needs to check his firewall though if they
do look like that (ie. if they say "Messenger Service" at the top), it's not configured properly because it
really shouldn't be letting those through.
The other possibility (if he gets it mainly when surfing) is that his browser is allowing popups to be opened - he could try downloading the Google toolbar and setting that to kill popups, that should help a bit.
Alternatively he could try a different browser, something like Firefox for example.