I love Friends tv show. I never missed any episode of it. I always download it's all episodes through this link:-
http://friends.download-tvshows.com/
It some time happens that you can get virus while you watching tv serial. it is common thing virus on internet. So you should use any good antivirus to be safe from the virus...
Here you can watch or download all episodes of Frinds... http://downloadfriendsepisodes.edogo.com/