There really isn't an equivalent file for Excel.

Excel does have a couple of template files that it uses.  

Book.xlt and Sheet.xlt (both located in the XLStart folder).  The book.xlt file
is used as the basis for new workbooks when the user hits the New Icon on the
standard toolbar.  Sheet.xlt is used as the basis for new worksheets added to
existing workbooks.

Lots of people have a file called personal.xls that is also stored in the
XLStart folder.  People use this file mostly for macros that they want available
when excel starts.  

These files may not even exist for your husband.  And the personal.xls file can
be named anything he likes (if he has one).

ps.

Saved from a previous post:

I have a short list of things to copy/update when we changed pc's at work.

It's not complete, but may help you.

Word/Excel files:

FileName     Use
custom.dic   personal dictionary
*.acl        personal autocorrect list
mssp2_en.exc personal exclusion dictionary
normal.dot   default (for new documents) template
*.dot        Any other templates you've made

*.xlb        personal toolbar
book.xlt     defaults for new workbooks
sheet.xlt    defaults for new worksheets
personal.xl* personal macros
*.xlt        Any other templates you've made

And don't forget any:
Local files  (If you don’t store on LAN)
(Settings)   Directories and other defaults (Tools|Options stuff)

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I've found the easiest way to find these files is to use Windows start
button|Search.

Remember to look through hidden folders/files.  And if I find multiple files of
the same name, I open excel (say), then make a minor change to that file.  Then
search again.  Then I can pick out the current version of the file.

That said, if you're upgrading from an older version of office, I wouldn't copy
the toolbar.  (I would take good notes to help me rebuild this toolbar (maybe
even fix it up a bit).)

Same with the normal.dot (I'd let MSWord rebuild that--then just copy|paste any
macros into it manually.)

The *.xlt (book.xlt, sheet.xlt), I'd copy over, but then open and resave them
using the newer version.