You can create a new default template, with your preferred fill colour:
Create a new, blank workbook.
Choose Tools>Options
On the Colour tab, click on the yellow square
Click Modify, select a colour as the default, click OK
To make yellow available, select the square that has the same colour
as the new default, and change it to yellow
Click OK.
Choose File>Save As
From the Save As Type dropdown, choose Template (*.xlt)
Name the File "Book.xlt"
Save it in the XLStart folder
(you can search for this -- in Windows XP it may be in
C:\Documents and Settings\UserName\Application Data\Microsoft\Excel)
When you click the New button on the toolbar, the new workbook will be
based on this template.
