There's also the 4GB enabler (ability to use 4GB of mem) and NVSE, which is required by a lot of mods.
4GB enabler http://newvegas.nexusmods.com/downloads/file.php?id=35262
NVSE http://nvse.silverlock.org/
If you load a huge number of mods, the 4GB enabler may be necessary to keep things humming.