Heres how you might do it in Office 2010 with an Office Language Pack.
Well need to install a language pack to get spelling checking in both languages.
you’re free to see all of your installed interface and proofing languages from the Office Language Preferences.
This will be listed under the Office Tools in your start menu.
This will show the editing and display languages you have enabled.
When the installer opens, select which product to add a language pack for.
Accept the license agreement, and then click Continue.
Click Install Now to implement the Language pack.
The installation may take a few minutes, so be patient.
Now it should be easier to read in your native language!
Youll also now notice that you have the proofing tools installed for your new language as well.
Click Ok at the bottom when youre done.
Youll see a prompt reminding you to close all Office apps.
Next time you open them, youll see the user interface language of your choice.
Feel free to switch it out as you need.