For the problems cause by Vistalizator in my Win7, see this post.
My Win7 was installed by a MIS colleague and by default he installed it in Traditional Chinese. I prefer working with my PC in English environment. One reason is that I could more easily know the English keywords when googling if I encounter some problems with my system.
As shown in the following figure, I found my system (Win7 Professional) has no ``Display Language'' panel in the Region and Language settings.
I clicked ``How can I install additional languages?'' link and the Help information told me:
The Display language section will be visible only if you have already installed a Language Interface Pack or if your edition of Windows supports a language pack. Language packs are available only in Windows 7 Ultimate and Windows 7 Enterprise.
Okay. So I guessed I cannot change the display language by installing additional language package in my Win7 Professional.
Luckily, I found Vistalizator do the work for me.