Setup

I had Office 2000 installed and tried to add Office Standard 2007 as an
upgrade.
When I tried to use one of the applications, Excel or Word, it said that a
..dll file was missing.
I tried to change or uninstall Office 2007 (unsuccessfully) and got the
following error: 'The language of this installation package is not supported
by your system"

I would appreciate your help solving this problem.
Thanks