Information Technology Blog - Galido.net

Running multiple versions of Microsoft Office is very possible if you take the appropriate steps and install the different versions in the correct order.

Here is an article from Microsoft on how to appropriately do so. Also mentioned is how to disable the auto installer that commonly executes when launching back and forth between two versions.

http://support.microsoft.com/?kbid=928091

To enable one Office application version to default over another, use the /regserver switch. (to unregister, use /unregserver)

For example: "C:\Program Files\Microsoft Office\OFFICE11\excel.exe" /regserver