How to use Office 2010 when another version of Office is already installed.
A nice KB2121447 Article from Microsoft!
How to use Office 2010 suites and programs on a computer that is running another version of Office
This article contains information about using Microsoft Office 2010 suites and programs on a computer that is running another version of Microsoft Office.
This article also provides advice to help prevent different versions of Office from conflicting with one another.
Information about how to use Office 2010 suites and programs on a computer that is running another version of Office