It all depends on what you want to do. It is absolutely not necessary to
uninstall the old product before installing the new one. Indeed, it is
possible to run multiple versions of Office suite on the same machine
http://support.microsoft.com/kb/928091. The only exception is that
Microsoft Outlook can only be run only in one version - either the old
version (not a good idea anyway) or the new one.
If you have enough disk space, then you should clearly keep the old version
as you may want to get used to the new Ribbon system in Office 2007 and
Office 2010 but you will get the option to remove the old version should you
wish to when you install the new one.
Hope this helps.
"MAR" <MAR@discussions.microsoft.com> wrote in message
news:6662680F-A931-4B70-A3DC-1BE2BD59A6E0@microsoft.com...
> Need to know if I have to uninstall old Office to load new one. Is it more
> efficient?
> thanks..