If and when a complete problem report, including the standard PC Gaming Computer hardware component summary, and a routine software environmental description is provided, along with full symptom details, then perhaps someone here will be able to offer a suggestion. Sorry to have nothing else for you now.
http://www.gamesas.com/index.php?/topic/1123068-what-that-dxdiag-thing-includes/
http://www.gamesas.com/index.php?/topic/1128654-can-we-cut-down-on-some-of-the-constant-frequently-asked-questions-around-here/
http://www.gamesas.com/index.php?/topic/1144076-some-trouble-shooting-assistance/
Incidentally, AFAIK, that video graphics device you have is not intended to be used for games, only for business, so you shouldn't be expecting much from it.
(Fallout: NV uses an ancient, obsolete game graphics engine, gamebryo, so that it ought to work at least somewhat, for this one game, with its lenient requirements, but should most likely fall on its face in most anything else other than MMOs and casual type games.)
Gorath