From Nexus Wiki
I was having trouble with my console window. I'm using windows XP Pro. When I would bring up the console I would only see the tale end of the text. Like it was shifted off the southwest of my screen. I found a fix the worked and it was simple.
- open My Documents\My Games\Fallout 3
- open the Fallout.ini file and scroll down to the [Menu]
- Change iConsoleTextXPos=30 to iConsoleTextXPos=230 and save.
Restart the game and try your console menu again.
(It's the ~ key on the upper left of your keyboard)