Here's a neat trick to add Pinyin or Zhuyin to any Chinese text. In Microsoft Word, paste some Chinese characters.
Select all the text (CTL A) and click on the file menu: Format > Asian Layout > Phonetic Guide.
The selected text will have phonetics, and there are a few options for positioning them and changing their size.
If you are seeing Zhuyin phonetics and would prefer Pinyin, (or vice versa) you may need to change the formatting of the Chinese characters. Select the text, click on the file menu: Format > Reveal Formatting. In the sidebox that pops up, you can change the language settings to PRC for Pinyin or Taiwan for Zhuyin.
If you still can't see the Pinyin phonetics, you may need to install MSPY (Microsoft Pinyin Input Method), available from the Microsoft website: http://www.microsoft.com/china/windows/products/ime/MSPY2007.mspx
You can find more information about this feature from Pinyin Joe's Chinese Computing Help Desk.