I have 2 versions of FNV on my hard drive. One is the Steam version and one the GOG version, the Steam version is uninstalled as I have been playing with the GOG version since it came out.
I recently was going to completely uninstall and reinstall FNV because I downloaded some mods which completely FUBARed my game. It was my fault as I installed these mods all together instead of one at a time to test them to see if they would be compatible with the mod build I wished to start my game with. They were three mesh mods and CASM and completely wrecked my game. I figured it would be best to start with a vanilla game as I did not know if just uninstalling these mods would remove all files that may have been installed by those mods.
I fired up Revo Uninstaller, which I use to completely remove a program and all it's files and found both versions of FNV on it. What surprised me was that it said the GOG version was 32-bit from GOG.com and the Steam version was 64-bit from Obsidian Entertainment.
As my machine is 64-bit it would seem like I would be better off playing with the 64-bit version. My question is would it make that much of a difference? Frankly I detest Steam as a site and the less they have to do with my games the better. Over the past several years I have come to believe that when there is a problem with a Steam game Steam is just as likely to be part of the problem as they are to be part of the solution.
However if there is going to be a significant difference in game-play I would bite the bullet and install the Steam version.
I need some advice on this from those more knowledgeable than I on this matter.