Holy mother of God, no.... No.... Please no...
Umm... Let's see... Wolf-BR had all new sounds in his mod. Since he released that and it's open scource, we can use those. They're better than the originals, except for the rifle. The rifle is the only one that I would say needs to be fixed. I'll post them all up in a second considering the link to his mod is dead.
I have only two copies of the mod on my computer(the two most current versions- b6 and classic), later, i post new links.
ok, the most aliens sounds are from AvP 1 and natural selection 1.
the acts textures = HL2 DM(fre game, if you have a ge force),
weapons sounds = various sources, some from hl/hl2 mods, others free games and cs weapons skins(game banana, custom skins),
MD sound are from shogo(I edited the sound a bit, but, not all sound are from shogo).
Do not worry but, so releasing new models with the 1.2, I make a mod with new skins/effects and sounds : )