Excel doesn't have an equivalent.

Although, it has a couple of files that you can use:

If you create a file named book.xlt and store it in your XLStart folder, then
excel will use this template file whenever you click on the new icon on the
standard toolbar.

You can also create a file named sheet.xlt that will be used as a template
whenever you insert a new worksheet into an existing workbook.

And many people create a file named personal.xls to store macros that they want
available each time they open excel.  This file is stored in the same XLStart
folder.

The XLStart folder's location varies with different versions of excel and
windows.  For me (xl2003 and winXP home), I use:

C:\Documents and Settings\(username)\Application Data\Microsoft\Excel\XLSTART

One of the differences is that there is no connection between the template files
and the new workbook/worksheet in excel.  In MSWord, you can tell what template
file the document was based on (IIRC).