I investigated scheduled tasks:

in Run,

"C:\Documents and Settings\All Users\Start Menu\Programs\Microsoft
Office\Microsoft Office Excel 2003.lnk" book1.xls

in Start-in

c:\

CommandLine gives

"C:\Program Files\Microsoft Office\OFFICE11\EXCEL.EXE" book1.xls


However:

On opening, the Macro security dialogue pops up unless it is set to Low.