Does anyone do this? That is to say, copy their cleanly installed Fallout 3 directory (all 4-5 gigs) into new ones, to then be modded individually to try out different sets of mods that are incompatible? For example FOOK 2.0 and FWE. Both are awesome, but have difficulties. Or extreme weather mods...like the nuclear winter. Lots of possibilities and you wouldn't have to deal with the hassle of removing those kind of mods if you didn't like them, just delete the directory and go back to your reference build. I've been experimenting with it, and it does work but I've run into problems where archiveinvalidation invalidated! only works for the primary install, not the copied one. Which means problems with mods not working...you have to manually create the archiveinvalidation.txt file yourself which is a pain if you want to run heavy mods. Should mention that you can't install fallout 3 twice, the dvd will try to uninstall, it's like the registry only wants to see it once. And the archiveinvalidation invalidated! app cues off the primary install. This sounds complicated...lol. If anyone's got it working, I'd love to hear how. =)