I dont know what are you talking about but here is my game list on Steam I had Fallout 3 and I am not lying.
http://steamcommunity.com/id/acare84/games
Secondly I bought the DLC from GFWL. I bought a 1600 MS Points card from here.
http://www.maximuscards.com/
And added points to my US Live account then bought the DLC got it? Then this annoying error was happenned. Then I use DoW2 beta key to log in to LIVE from Fallout 3 and It worked. So I can log in the LIVE from the game and I can play DLC too because DLC is tied to your account not CD Key got it?
I installed the OS` frequently because I bought a new computer and I tried the game on Windows 7, Windows XP and Windows Vista. I don't care about achivements I am not a console gamer.
Finally I post this to Steam forums, Yougamers forums, Bethesda forums and GTA forums because I want to warn the people about this. I paid the game but I cant use all features when I am installing frequently and there is nothing written about this on game manual or eula.

Hum. If your telling the truth then I'm sorry, but your just going to different forums copying and pasting the same thing.
It may be different in Turkey, but usually people in America do that to troll.
If you are asking for help, then I apologize.
And if you noticed, I don't use GWFL. If this is true, I won't be.
I do notice after reading your posts you are genuine, and your not a wise ass trying to annoy people. Kinda hard to tell sometimes >_<

what potential do you foresee?

Not sure about that. GTA IV has been installed/uninstalled 20 + times on my computer, because I still can't figure out how to make the damn thing run well, and it's never given me any problems.

Much the same as xbox live, a good solid multiplayer platform with integrated marketplace/addon options, patching and pointless addons like achievements. Basically what they've done but with a non-intrusive and functional protection. Ideally they should use GFWL as their only source of DRM and not doing that thing with requiring you to be online for everything, like accessing saves.
Oh and letting EVERYONE use it or it's only going to increase piracy, if you can't play dawn of war 2 (that you can probably legally buy) because you don't live in GFWL supported country then youre going to download it. From what I understand, the commercial aspect is the reason it'd not in every country and they've dropped the entire service instead of just disabling the marketplace which is what would seem to be the easiest and fairest thing to do.
That said I don't own any GFWL games, I'm only speculating based on what I've read

What's it like, being unable to play a game well that you paid for?

Kind of like Fallout 3!!!!

I don't actively HATE steam, I just don't want an application running that I'd use none of the features of. If I had to have an application like that, I'd prefer a GFWL application because of a possible interoperability with xbox live that I and my friends already have.
To be blunt, I'll USE steam when I can get a game computer up and running and when I get empire total war & dawn of war 2 and to be honest I won't give a toss whats running on it because it'll be a dedicated gaming machine and as long as games run well, thats all I'll care about. With either application I'll just be wondering what on earth the point of having it is if the most function I ever use is to send a mate on xbox live an abusive message occasionally

Not very fun. Though most of it's my own fault, as I didn't pay enough attention to the system requirements. My CPU is nowhere near the speed I need (yet) to get a nice and steady framerate.