Do you use Steam? If not you can use this: http://modsreloaded.com/fo3-ram-boost. Just apply the instructions to NV instead of Fallout 3.
If you do have Steam to not use the ram boost. It does not validate with Steam and cause corruption. I suggest making a backup of the FalloutNV.exe anyways.
Here is the second option:
1) Download this mod: http://www.newvegasnexus.com/downloads/file.php?id=41381
2) Follow the instructions on how to set up with FOMM.
"Fallout Mod Manager (Integration, not needed but recommended):
- Run FOMM
- Press in Settings button
- in the last Tab, in Custom Launch Command, put the exe name Fallout_Fullscreen.exe"
3) Download the 4gb enabler off of the http://nvse.silverlock.org/ website: This will allow you to have the 4gb enabler without conflicting NVSE.
If you do not have NVSE (Though you should) you can find the 4gb loader here: http://www.newvegasnexus.com/downloads/file.php?id=35262
Do not use the 4gb enabler from the nexus with NVSE, use the one they provide on the NVSE page.
Just place the 4gb exe and 4gb helper in your NV directory and the Fake Fullscreen should detect it and run it. This is provided you run your game with the Fake_Fullscreen.exe.
Hope that helps, because both help me.
Edit: The Fake_Fullscreen.exe also detects NVSE.