The worst part is you can't just jump back into the game; you need to ease into it; and that place is one of the worst places in the game if you aren't on the ball.
I got to the pitch black place where you have to give up your shield for a lantern. Already have it on 360 so not really excited about the PC port, I will be getting the DLC though.
Not sure how active the fallout modding community is but I used
No Mutants Allowed
http://www.nma-fallout.com/#
to find some mods when I played the games.
The reason I stopped playing WoW was because I ran out of stuff to do. I'm sure there will be a solid play base of more casual players, but to break into the mainstream they are going to have to provide continual end-level content.
I thought there were already plenty of mods. Like this one that add multiplayer http://www.gameinformer.com/b/news/archive/2011/12/16/skyrim-mod-adds-multiplayer.aspx
I'm also running Windows 7 64 bit. Bought the DLC through the windows marketplace, then had to install it twice (the first time I got an error so had to delete it)