I have the GOTY PC version. In the Fallout 3\Data folder on my hard drive are multiple BSA and ESM files for all of the expansions. This is my first time playing the game and according to the manual, as soon as I leave Vault 101 I should have gotten radio messages, new map markers and quests log entries for all of the expansions. That did not occur for me.

I do not have a Windows Live Gamer account because I did not think that was necessary since the expansions were part of the GOTY edition

Can anyone tell me what I need to do in order to unlock the expansions?

Thanks

Use FOMM to order them (directly after Fallout3.ESM in chronological order of release) and make sure they're ticked on? Provided your DLC ESM's are in your Data directory and are active, all should work all right.

Why would I need to install a 3rd party mod manager in order to get the DLCs that came with the GOTY edition to work properly?

Did you make sure to place the X in the box in the Data Files section of the launcher?

Also FOMM is used for all mods/dlcs for most people because it has more features and cleaner UI then the built in one. But for this, the one in the Data Files section of the main launcher is good enough.

That explains it. The manual says nothing about enabling the DLC in the Data Files section. That resolved the problem. Thanks

Mostly, to enable load order manipulation. FOMM has many other useful features as well.