I would use a macro:
From Chip Pearson:
http://cpearson.com/excel/case.htm

If you're new to macros, you may want to read David McRitchie's intro at:
http://www.mvps.org/dmcritchie/excel/getstarted.htm

Instrument Guy wrote:

I have been sent an Excel spreadsheet and asked to change the text from
uppercase to lowercase. I could do this manually but it is quite a large
file. Is there a way to do a global change?

--

Dave Peterson