english windows and 速成/倉頡輸入法

I don't know wheather the difference between vista and xp, but they should be more or less the same, you can try and find it out.

在英文版 Windows XP 顯示中文及安裝輸入法

在英文版顯示中文

in〔Control Panel〕→〔Regional And Language Options〕→〔Language〕
select〔Install files for East Asian Languages〕Install

在英文版安裝中文輸入法
in〔Control Panel〕→〔Regional And Language Options〕→〔Language〕
→ 〔Detail〕→〔Install Service〕→〔Add〕→
in〔Input Languange〕select〔Chinese (Taiwan)〕
in〔Keyboard Layout/IME〕choose速成(simple input method) or倉頡

圖片參考：http://polyart.com.hk/nop/n30.gif