GFLW worked for FO3 only when you ignored it completelly by always playing in offline mode. In online mode it was a royal pain. People asking for it should instead ask for no online component at all please.
Funny, I got a disc that had all of the FO3 DLCs on it which didn't require GFWL and cost less than buying them individually online.
Also, you can simply move your savegame files into the "online" GFWL save folder for your profile and voila! They can now be played while logged in.
GFWL>Steam