UAC = User Account Control. It's a security feature introduced in Vista that can cause problems with modding games if you've installed them in the default C:/Program Files folder. It prevents someone from actually writing anything to there unless you turn it off or run as an administrator. It's recommended that you install any games like Fallout, ones that you're going to be adding mods to, into a seperate folder outside Program Files, something like C:/Games, so you can avoid those security measures altogether.
Thanks for the reply - I knew that, but I was just having a major "senior moment" there. And I actually did install my FO3 in a C;\games folder on my drive to avoid probelms with the default install location.
I'm going to put on a bib now so I don't dribble tapioca pudding down the front of my shirt. :blush2: