Can't launch game cause its requires xLive.dll and don't want to install useless abandonware as GFWL is?
So here's an easy solution for you: just unpack .dll file to your Fallout 3 game folder (where .exe files is) and launch game via FOSE .exe file. Yep, that's all.

Warning: i commend to launch game via
The Fallout Script Extender (FOSE)

This is original (signed) .dll file that was installing with GFWL in SysWoW64, please let me know if this fix not working with x86 systems, cause i checked it only with x64. All rights belong to Microsoft Corporation.

Have a nice game.