Windows XP supports "QuanPin"
Control Plane ->Region and Language Setings->Language->Install Asian Character->OK
Control Plane ->Region and Language Setings->Advance->"Default language for non-unicode program" choose "simplified chinese"->OK
Control Plane ->Region and Language Setings->Language->Detail->Choose input method (for example, Chinese->quanpin)
You can also download Windows Pinyin input method 4.0 (search "mspy" at google.com).