I am using Excel 2003, and am trying to share my workbook with someone who is
using Excel 2007. I have signed my macro using a digital certificate I
created using selfcert. However, when I send this to someone else using
excel 2007, it says that the certificate is invalid, and they cannot run the
macro. I realize that selfcert keys are hardware-encoded, however I have
been able in the past to share these types of macros with people using Excel
2003 just by having them accept me as a trusted publisher. Is there no way
for me to do this in Excel 2007 aside from having them add a trusted
location?

If this way does not work, is there any way for me to write macros using my
Excel 2003 and share it with other people using Excel 2007? If I was using
Excel 2007, would this be any easier for me?