If you do not come from an English speaking country most probably your System Locale on Windows (XP/7/8) is set to the country you originate from. I personally, even after a Windows reinstall use Bulgaria as System Locale so I don’t have problem reading/writing Cyrillic.
Case 1:
If you happen to be reading this before installing Gimp read on:
1. After you run gimp-2.xx-setup.exe you need to click on “Customize”.
3. Proceed normally installing and using your favorite Graphic IMage Processor 🙂
Case 2:
If you already installed Gimp and you want to change the Language to English. Follow these simple steps:
1. Start Menu > Computer > Properties
2. Advanced system settings
3. Click on “Environment Variables…” button
5. Create a variable with name lang and value c.
6. Click Ok, Ok and restart Gimp. Now it should start in English.