Win XP
Go to Control Panel > Regional and Language Options >
Languages Tab > Check "Install Files for East Asian Languages"
> Click "Details" > Click "Add" > Input Language: Chinese
(PRC) > Keyboard Layout: Chinese (Simplified) Microsoft Pinyin
IME 3.0
Done.
To switch between input languages, press Alt + Shift. Or press the
small icon at the lower right hand side of your screen that says
"EN" or "CH".