QUOTE(BanditFlyer @ Dec 27 2005, 05:10 PM)

it looks we were looking for different solutions
Actually we were looking at
different problems 
This is funny

I could have sworn you asked how to compare word files in excel

but on rereading your initial messages plus your latest comment, this is likely what you want (if it worked in Word it'll work here, they do reuse some code between those apps):
From Excel Help I quote:
QUOTE
Turn on change tracking for a workbook
On the Tools menu, click Share Workbook, and then click the Editing tab.
Select the Allow changes by more than one user at the same time check box.
Click the Advanced tab.
Under Track changes, click Keep change history for, and in the Days box, type the number of days of change history that you want to keep.
Be sure to enter a large-enough number of days because Microsoft Excel permanently erases any change history older than this number of days.
Click OK, and if prompted to save the file, click OK.
Note Turning on change tracking also shares the workbook.
Excel in Office 2000 and Office 2003 have tools/share feature. I don't recall about 97.
The only advice at this point I'd add is
PLEASE have a backup of BOTH files before you enable sharing. We've seen sharing sometimes caused some problems, unfortunately I can't remember what.