To enable Language Bar on Windows XP please follow these steps -

1. Go to Control Panel > Regional and Language Options
2. Select the "Language" Tab and then click on the "Details" button.
3. Go to the Advanced Tab.
   Under System Configuration section uncheck the "Turn off advanced text services"
   
   
4. Go to the Settings Tab
   
   
5. Click on Language Bar button and make the settings as per the image shown below.