Translation question?

Hi,

i am translating my site using .mo files so i wonder if it possible to have multi lang site with .mo .po files

for greek psts-el_EL.mo, psts-el_EL.po
for english psts-en_EN.mo, psts-en_EN.po

is that possible to have muti lang with multi .mo and .po files.
if yes do i need to make any chanegs any where?