Just deleting the ini files won't do you any good; some of them are constructed by the installer as opposed to the launcher. If the launcher isn't picking up your Video Card, make sure that (If you replaced the old one) your old drivers and device entries have been completely removed from Windows. If you just installed a new card and had been using, for example, onboard video, make sure that the onboard video is disabled in both windows and the bios.
Then run FalloutNV's default launcher, and the setup options. If that doesn't work, completely reinstall FNV by:
1) Delete Local Cache through Steam.
2) Delete your SteamApps\Common\Fallout New Vegas\ folder through Windows Explorer.
3) Delete your My Documents\My Games\FalloutNV\ folder through Windows Explorer.
4) Reinstall FalloutNV through the Steam Library.