So I accidently deleted Fallout_Default.ini and now it prompts me to re-install Fallout: New Vegas.
Hehehehe.. I can do this without losing my save files, RIGHT?! :woot:
You shouldnt even need to reinstall. Just verify your local game cache.
game cache:
1) Open Steam
2) Right click on Fallout: New Vegas
3) Hit Properties
4) Click the "Local Files" tab
5) Click on "Verify Integrity of Game Cache"