How do I stop Excel growing large after changes?

How do I stop 2003 spreadsheets automatically opening in Excel 2007??
I currently run a Win 2003 server with Office 2003 installed.i have recently
installed Office  2007 .
I need spreadsheets created in Excel 2003 to be opened (by default) with

I get error message 1311 Source file not found.  Verify that the file exists
and you can access it.  I get this message everytime I try to open excel in
my email.  I have basice edition 2003, and all applications open correctly,
but not as attachment.  Please Help

I have numerous spreadsheet that I've been using for the past ten years. Way
back when I created macros to sort the data in various ways and then assigned
the macros to control buttons. They always ran just fine until we upgraded to
Excel 2003. Now the problem.

Need to creata a monthly tme sheet. to report consultant's activites,
including meetines and phone calls

I have a spread sheet with a list of users sorted alphabetically.  I'd like
to sort that data by userID on a different tab.  Problem is, I don't want to
manually do it.  Is there a way to have the 'ID sorted tab' automatically
update and sort itself as I make changes to the ...

I'm preparing a worksheet with many formulations and formated cells, I would
llike to share this Worksheet with my colleagues so they van enter data and
get results without being able to modify, change or delete any of the
formating or formulations.