Using Office 2007 with Windows XP; working in compatibility mode for 2003;

We have a legacy program in which a series of sheets are copied from an
Office 2007 file into Office 2003 Files. However, we find that this cannot
even be done manually because the relative sheet sizes are different.

These sheets do not contain data below about 3000 rows, so nothing would be
lost if the sheets were cropped during the copy procedure (at the moment the
entire sheets are copied).

What are my options? We need to keep the source files in 2003 format for
many users to have access. Revert to Office 2003 in the program file? - is
that the only realistic option here or is it possible to somehow force a copy
and crop the sheet?

Many thanks for your assistance.