I'm on a PC. I know it's old but I just bought the game and I want the official addons. The in-game option "microsoft windows for games" says that it has stopped selling everything for PC. How do I buy the 4 official addons now?

Where did you buy the game? Nowadays, all there is on shelves (and Steam) is the GOTY edition for $19.99. The GOTY edition has all the DLC on it. If you got Fallout 3 by itself from Steam (non-GOTY), the DLC should be on Steam but if you got the non-GOTY from a store then I do not know how you can get DLC.

I think IT IS the GOTY edition, but I bought it at a Walmart for $6 in a bin with some other stuff. I have New Vegas and Skyrim on steam, and their application which starts whenever I start one of them. Will the addons I buy from Steam work with all Game of the Year Editions, or do I have to buy Fallout 3 from Steam, for the addons to work?

The Fallout GOTY will have "Game of the Year Edition" on the retail box. It will also list the additional content on the box. It will have 2 discs. One is the main game and the other is the DLCs. If you only have one disc, you do not have the GOTY.

Yeah, you're right, it's not. On the back it says "Winner of Show", not "Game of the Year". It's updated to 1.07 though, will it not run the addons from Steam?