Just have to say, i've installed this supermod for fallout 3 and it's put an entirely new zest into the game for me. This mod, IMO, is a must have. Fallout 3 was boring to me, now, i can't wait to play it and when i do im glued to the chair. It makes the game much harder, but much more engrossing. It's probably what fallout 3 should have been at release.
Anywho, the mod is called:
Fallout 3 Wanderers Edition (FWE)
Homepage here:
https://sites.google.com/site/fo3wanderersedition/
D/L site here:
http://www.fallout3nexus.com/downloads/file.php?id=2761
If you follow the install instructions carefully, you'll get it going without a hitch.
I've been running this supermod with a graphical mod called:
Fellout:
http://www.fallout3nexus.com/downloads/file.php?id=2672
You maybe tempted to run JSGME (ive ran it with lots of games), but id advise to just stick with Fallout Mod Manager.