Did they just prepatch it with a xlive.dll to remove gfwl?

According to various staff posts so far GOG has:
Ripped out Games for Windows Live from affected titles (so any problems caused by it should not affect GOG versions)
Ripped out all Steam related stuff so games no longer require Steam.
enabled LargeAddressAware flag in executables allowing games to access more memore (less change of out of memory related crashes)
included bUseThreadedAI=1 and iNumHWThreads=2 in the ini file (prevents problems related to multi-core computer setups)
Also GOG installers are usually programmed to set any required compatibility setting for games on installation

Basically the GOG version works. The Steam version doesn't.

I had NV on Steam and when the GOG version came out I decided to start up my Steam version. Black screen crash as soon as I started it. Spent 10 dollars for the GOG version and haven't crashed once, got up to level 10 twice now. I am a serial restarter when adding mods.

Well that ain't true but some GOGers are stupid enough to believe you.

It's just that GOG games are more likely to work than a Steam release. Some Steamers are stupid enough to.... buy from Steam.

1) Steam version isn't optimized for Windows 7 or later, GOG version works on Windows 7 / 8 /10
2) GOG version has cloud saves.

I've bought Fallout 3 on Xbox 360, Xbox One, Steam, and GOG. I may be stupid, but it's one of my favorite games.

My wife paid $55 for GOTY on 360. That's the most we've spent on it. It was like $5 on XB1. That's a digital download. I've since given away the GOTY set which would have worked. I don't like switching discs though. I want to be able to just pick up the controller and play. It's worth it to me to not have to get off the couch to change the discs if my wife left Rockband 4 in or I forgot to take out the last Blu-ray I watched. On Steam it was like $6. I dunno. It was cheap. I bought it on GOG because I didn't want to put Steam on the laptop. It'll be fine once I get an SSD in it, but as long as it's still spinning on steel platters, Steam is just too busy for me. On the laptop, anyway. And GOG is super awesome, deserves the support.

I bought Fallout 3 on Gog yesterday because everyone said it works perfectly. I was happy for the 1st 3 hours and now the game freezes everytime I enter the water processing plant in Megaton forcing me to log out of windows 10 because alt+tab and alt+F4 don't work.
I've been trying to play fallout 3 since I migrated to win10 from 7 where it worked nicely like 2 years ago it's very annoying. I thought Gog was the answer, apparently it isn't.

If someone can help, I'll be very grateful...

That is the biggest gaming mistake to be made, unless your playing the windows 10 only games. Windows 10 only runes 10 only games decently, while making any other games go poor.

Gog is best, DRM free = Way to go.

Steam ( I don't have ) supposedly resets so it logs you out or slows down after too long a time without updates,
thats DRM + Internet. not sure if that is true though.

Actually I fixed my issue. It was a compatibility issue and 1 mistake on my part (I wrote a wrong number in the ini causing the game to go crazy) I even fixed my mouse acceleration and the stuttering. Now it's almost perfect.

I quicksave a lot in the GoG version since it crashes a lot. But still, it's playable and not nearly as bad as the Steam version.

you crash a lot? After I fixed my issues I haven't had any other bug or crash, hope it stays that way. Have you change the 2 lines in the ini file:

bUseThreadedAI=1
iNumHWThreads=2

Around the upper section of the file

I do quicksave a lot too, I don't know if it prevents me from crashing, but try that if you haven't already... you never know.

Hello, I just bought Fallout 2, Fallout NV and Fallout Tactics during the GOG summer sale. However I already have Fallout 3 GOTY edition on steam as well as the base game on Xbox and didn't want to pay for a 3rd copy on GOG.

I was able to start Fallout 3 GOTY edition on steam by signing up with GFWL. Are there any patches you recommend for the steam edition you think I would need to avoid crashes? Thank you.

I personnally spent 2 years trying to make it work on steam, never succeeded. Reason why I bought it a 2nd time on GoG
If the Nexus unofficial patch, the 2 modified lines in the ini files (see my post above) and other fix you can find on the forums don't work, then it will probably never work on steam.
I wish you luck