Depending on how you upgraded excel, you may have multiple XLStart folders. And
if you have multiple book.xlt throughout those folders, excel may not use the
one you want.
To find the current XLStart that excel wants to use...
open excel
hit alt-f11 to get to the VBE
hit ctrl-g to see the immediate window
type this and hit enter:
?application.startuppath
For me (winXP and xl2003), I get:
C:\Documents and Settings\(username)\Application Data\Microsoft\Excel\XLSTART
Find all the book.xlt files you can (or check each of the XLStart folders you
have).
Close excel
windows start button|search
look for book.xlt
And delete/move/clean up the ones not in the correct location.
(I'd delete all the "wrong" book.xlt's and just keep the one in that folder.)
Then when you click the New Icon on the standard toolbar, you should get a
workbook based on that template file.