You could probably get Excel to handle that for you quite easily with an
Excel macro that gets launched automatically every time Excel is started.

I don't know what statements you'd put in that macro myself - I only just
learned to write Word macros the other day and haven't tried Excel macros
yet - but it shouldn't be too hard to do what you want.

The language used for Word and Excel macros is VBA (Visual Basic for
Applications) and there are many resources for this language online; just
search on VBA in Google. There are also some public Microsoft newsgroups for
discussing VBA that I found very useful, particularly
microsoft.public.word.vba.general. (You'll need to add the Microsoft news
server, msnews.microsoft.com, to your newsreader, then simply subscribe to
microsoft.public.word.vba.general. Or you can read and post via Google
Groups if you don't have a newsreader program and don't want to bother with
one. Mind you, Outlook Express has a built-in newsreader so you shouldn't
need to install anything new unless you really hate Outlook Express.)

--
Rhino