I have downloaded the OS 4.5.0.81 on Blackberry site. It is a EastAsia version with Chinese, Korean, Japanese and have INPUT method support for all the languages including simplified and traditional chinese.
If you need Asian language, this is a MUST. This is what I used:
8120EastAsia_PBr4.5.0_rel81_PL2.7.0.68_A4.5.0.55_I ndosat.exe
I have used it for a few weeks on my 8120. Rock solid.
But make sure you add back what you need for your carrier......