Depends, all Services (IE WinMedia, Spinner, etc) or specific services?
Realplayer uses port 554 for Spinner
WinMedia uses a port 1755 for the music,and 80 for the content. You could block these ports, but then no content gets through, even for legit purposes, you could try to figure out all the IP's the services are using, but they may change, then your blocks all have to be re-done...
Also, a lot of providers are using port 80 now for everything, because it's rarely blocked at firewalls...
Mike