What is it exactly that you want to do ??
Do you only want to send text messages etc in Russian ?
Or do you want to recieve text messages etc in Russian ?
Sending SMS in a language not native to the phone is easy with a keyboard that supports the language - however any SMS received in a language not supported by the phone (in your case Russian) will not display correctly (you will get a message showing this : ?????)
If you have installed a keyboard which has Russian (and you have selected this language) then you can send SMS in Russian !!! - BUT the receiving phone MUST have Russian as a native language to be able to view it.
i.e East European firmware which includes Russian in the Locale and Text Settings.
A good keyboard is Smart Keyboard from Android Market - you also need to install Russian Language for Smart Keyboard and in the Smart Keyboard settings select it to use Russian language
you can get it from here :
https://market.android.com/details?id=net.cdeguet.smartkeyboardtrial&feature=search_result
russian language from here :
https://market.android.com/details?id=net.cdeguet.smartkeyboardpro.ru&feature=more_from_developer
If you want the phone to be able to view received SMS etc in Russian you will need East European firmware !
It does not matter which language you have set as default - the phone can display text from all the other languages that are pre-installed !!!
In my experience installing Locale Packs does not make the phone 'switch' to another language - basically if the phone has not got a language as standard then it cannot display another language correctly !!!
You say that you have 2.3.3 - is this an official update for the phone - or did you flash one using ODIN ??
Can you give me more information about your phone and i will try to help you more !
Cheers
Nevy P
p.s If you have already installed a keyboard which has Russian - have you selected to use it in SETTINGS/LOCALE AND TEXT/(TICK CHECK BOX)
Check this first and in the keyboard menu check that you have selected Russian as a language