Very simply; a more upbeat music theme for the load screen when you are booting up. "The Wanderer", from Fallout 4.
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I came to New Vegas from Fallout4, and just as with that game, I didn't really care for the mournful load music when you start the game. In Fallout 4 I found a mod that used "The Wanderer" Fallout 4 game trailer video (below), as the load video (I have not since then been able to find that mod).
Since New Vegas doesn't have a load video, I decided to use this theme music for my New Vegas load screen music. I have extracted the music track from the video, and used it to replace the "MainTitle" music file. To me it transmits a more adventurous feel to being the wasteland wanderer.
To install, simply drag/drop the Data folder into your root game folder. If you want to keep a copy of your original load theme, back up a copy in another location. Easy-peasy. ; )