So, after I bought the window 7 ultimate upgrade version (English) and install to my computer and want to run with Japanese Win 7 OS, and then I need to download the Japanese Win 7 OS via windows update and install it. And after that Can I instantly switch the OS between two languages which English and Japanese? OR, if I want to go back to the English version OS, Do I have to redownload the English Win 7 OS from Windows update again? My question is Work in the language of your choice and switch between any of 35 languages. means something Do I have to download and install it via windows update every time when switch the language or after I download and installed the other language (Japanese) and then Can I just instantly switch between two languages (English and Japanese)?

If your primary language version is English and you apply a Japanese language pack (MUI), you can easily switch between English and Japanese. (You can switch the display language and the keyboard layout.) If you want to return to English as the display (UI)language, you can do that without further downloads, just by selecting "Region and language -> Keyboard and languages" in Control Panel. You only have to do a new download if you need a third language.Mobile AMD64 3000+, VIA Apollo K8T800 chipset, 1 G RAM, ATIRadeonMobility 9700, 20x DVDRW, C:XPSP3 (55G),D:WIN7 (25G),F:DATA (250G)

I see. Thank you for info.