Pashuteh, you shouldn’t have to install a language pack
I only know how to do it on windows 7, because that’s what im using. Try to use these steps and see if they work.
On windows 7
1) go to control panel
2) press on clock, language, and region
3) press on region and language
4) press on the keyboard and languages tab
5) press change keyboards
6) under installed services, press add
7) select hebrew and under keyboard select hebrew and press ok
* make sure the default input language is english, otherwise everthing will authomatically be hebrew.
* to change b/w languages press left alt+shift
* if you want to type hebrew and you don’t have a hebrew keyboard access the onscreen keyboard (you can click on the letters on the screen or uses the regular keyboard to type hebrew letters.